UITableViewCell skipped in responder chain - ios

I'm attempting to trigger an event in a subview of a UITableViewCell, and let it bubble up the responder chain and be handled by a custom UITableViewCell subclass.
Basically:
SomeView.m (which is a subview of the UITableViewCell)
[self.button addTarget:nil action:#selector(someAction:) events:UIControlEventTouchUpInside]
SomeCustomCell.m
- (void)someAction:(id)sender {
NSLog(#"cool, the event bubbled up to the cell");
}
And to test why this wasn't working, I've added the someAction: method on the ViewController and the ViewController is the one that ends up handling the event that bubbles up from the table view cell subview, even though the Cell should handle it. I've checked that the Cell is on the responder chain and I've verified that any views on the responder chain both above and below the cell will respond to the event if they implement the someAction: method.
What the heck is going on here?
Here's a project that shows it https://github.com/keithnorm/ResponderChainTest Is this expected behavior somehow? I haven't found any documentation stating UITableViewCell's are treated any differently than other UIResponder's.

The cell seems to ask its table view for permission. To change that you can of course override
- (BOOL)canPerformAction:(SEL)action withSender:(id)sender
{
return [self respondsToSelector:action];
}
Swift 3, 4, 5:
override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
return self.responds(to: action)
}

I've concluded that this is either a bug or undocumented intended behavior. At any rate, I ended up brute force fixing it by responding to the event in a subview and then manually propagating the message up the responder chain. Something like:
- (void)customEventFired:(id)sender {
UIResponder *nextResponder = self.nextResponder;
while (nextResponder) {
if ([nextResponder respondsToSelector:#selector(customEventFired:)]) {
[nextResponder performSelector:#selector(customEventFired:) withObject:sender];
break;
}
nextResponder = nextResponder.nextResponder;
}
}
I've also updated my demo project to show how I'm using this "fix" https://github.com/keithnorm/ResponderChainTest.
I still welcome any other ideas if anyone else figures this out, but this is the best I've got for now.

You can change the code in View.m as
[button addTarget:nil action:#selector(customEventFired:) forControlEvents:(1 << 24)];
to
[button addTarget:cell action:#selector(customEventFired:) forControlEvents:(1 << 24)];

do like this
#implementation ContentView
// uncomment this to see event caught by the cell's subview
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if(self)
{
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setTitle:#"Click" forState:UIControlStateNormal];
[button setBackgroundColor:[UIColor blueColor]];
[button addTarget:self action:#selector(customEventFired:) forControlEvents:UIControlEventTouchUpInside];
button.frame = CGRectMake(4, 5, 100, 44);
[self addSubview:button];
}
return self;
}
- (void)customEventFired:(id)sender
{
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:#"Event Triggered in cell subview" message:#"so far so good..." delegate:nil cancelButtonTitle:#"cancel" otherButtonTitles:nil, nil];
[alertView show];
}
#end
now customEventFired: method get called

I think this one is the easiest solution. If you do not specify a target the event will automatically bubble up the responder chain.
[[UIApplication sharedApplication]sendAction:#selector(customAction:) to:nil from:self forEvent:UIEventTypeTouches];

Related

UISwitch value change event is not triggered iOS

I am adding the UISwitch programmatically in a scroll view.
UIVIew -> UIScrollView -> UISwitch
UISwitch *toggleSwitch = [[UISwitch alloc] initWithFrame: CGRectZero];
[toggleSwitch addTarget:self action:#selector(flipMode:) forControlEvents:UIControlEventValueChanged];
toggleSwitch.on = YES;
toggleSwitch.userInteractionEnabled = YES;
[scrollView addSubview: toggleSwitch];
Action method:
- (IBAction)flipMode:(id)sender{
if([sender isOn])
{
// On Toggle ON
} else {
//On Toggle OFF
}
}
When we toggle the switch multiple times or on dragging or moving the switch slowly from ON to OFF state or vice versa at some point of time the action is not getting called. In next moment on value change it will trigger the event.
Occurrence of this issue is 2 out of 15-20 trials. Unable to find the root cause for it.
Help appreciated
set your delaysContentTouches property of scroll view to NO
yourScrollView.delaysContentTouches = NO;
This will cause your switch to "get" the touches immediately, rather
than have them go to the UIScrollView first.
Check this answer.
your flipMethod: should look like below code
-(void)flipMode:(id)sender
{
if([sender isOn])
[toggleSwitch setOn:YES animated:YES];
else
[toggleSwitch setOn:NO animated:YES];
}

Deselect all UIButtons when one is selected

I have eight (8) UIButtons setup in my game. When one is selected it shows that it is selected and if you click it again it will show as unselected. However, I want to make it so that when you select a button and any of the other seven (7) are selected, they become unselected.
I know how to do this through the use of [buttonName setSelected:NO] but the problem is I can't pass buttonOne to buttonTwo if buttonTwo has already been passed to buttonOne because I have already imported buttonTwo's header file in buttonOne. It throws a parse error if I have both headers importing each other. I've been stuck on this for a while now and was hoping that someone might have a solution to my problem.
Thanks for any help.
Get the parent view of the current button and iterate through all the buttons inside, unselecting all of them. Then, select the current one.
// Unselect all the buttons in the parent view
for (UIView *button in currentButton.superview.subviews) {
if ([button isKindOfClass:[UIButton class]]) {
[(UIButton *)button setSelected:NO];
}
}
// Set the current button as the only selected one
[currentButton setSelected:YES];
Note: As suggested on the comments, you could keep an array of buttons and go over it the same way the above code does with the subviews of the parent view. This will improve the performance of your code in case the view containing the buttons has many other subviews inside.
I know its too late to answer this question but I did it in only small lines of code . Here is what i did :
NSArray *arrView = self.view.subviews;
for (UIButton *button in arrView) {
if ([button isKindOfClass:[UIButton class]]) {
[((UIButton *) button) setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
}
}
[button1 setTitleColor:[UIColor orangeColor] forState:UIControlStateNormal];
Simple way to do.
-(void)buttonSelected:(id)sender{
UIButton *currentButton = (UIButton *)sender;
for(UIView *view in self.view.subviews){
if([view isKindOfClass:[UIButton class]]){
UIButton *btn = (UIButton *)view;
[btn setSelected:NO];
}
}
[currentButton setSelected:YES];
}
I actually created an answer by reading all of your guys input, which I thank you greatly for. The tag property of the UIButton class was unknown to me before this post.
I created own subclass of UIButton, let's call it CustomUIButton.m. I created a NSMutableArray property for use when storing the buttons, which I'll call customButtonArray.
When I created the button, I set the tag property, and added the button to a local array on the parent view controller. After all buttons I wanted were created, I set the customButtonArray, like so:
// Initialize buttonHolderArray
NSMutableArray *buttonHolderArray = [[NSMutableArray alloc] init];
// Create a button
CustomUIButton *newButton = [[CustomUIButton alloc] initWithFrame:CGRectMake(10, 10, 50, 30)];
newButton.tag = 1;
[newButton setImage:[UIImage imageNamed:#"newButtonUnselected" forControlState:UIControlStateNormal]];
[buttonHolderArray addObject:newButton];
// Create additional buttons and add to buttonHolderArray...
// using different numbers for their tags (i.e. 2, 3, 4, etc)
// Set customButtonArray property by iterating through buttonHolderArray
NSInteger buttonCount = [buttonHolderArray count];
for (int i = 0; i < buttonCount; i++)
{
[[buttonHolderArray objectAtIndex:i] setCustomButtonArray:buttonHolderArray];
}
To deselect any other button selected when a different buttons handleTap: is called, I iterated through the customButtonArray in the subclass main file and set the selected property to NO. I also set the correct image from another array property that I manually populated with the images, which I did so the array didn't have to be populated every time a button was pressed. At the end, unselected all other buttons, like so:
// Populate two arrays: one with selected button images and the other with
// unselected button images that correspond to the buttons index in the
// customButtonArray
NSMutableArray *tempSelectedArray = [[NSMutableArray alloc] init];
[tempSelectedArray addObject:[UIImage imageNamed:#"newButtonSelected"]];
// Add the other selected button images...
// Set the property array with this array
[self setSelectedImagesArray:tempSelectedArray];
NSMutableArray *tempUnselectedArray = [[NSMutableArray alloc] init];
[tempUnselectedArray addObject:[UIImage imageNamed:#"newButtonUnselected"]];
// Add the other unselected button images...
// Set the property array with this array
[self setUnselectedImagesArray:tempUnselectedArray];
- (void)handleTap:(UIGestureRecognizer *)selector
{
// Get the count of buttons stored in the customButtonArray, use an if-elseif
// statement to check if the button is already selected or not, and iterate through
// the customButtonArray to find the button and set its properties
NSInteger buttonCount = [[self customButtonArray] count];
if (self.selected == YES)
{
for (int i = 0; i < buttonCount; i++)
{
if (self.tag == i)
{
[self setSelected:NO];
[self setImage:[[self unselectedImagesArray] objectAtIndex:i] forControlState:UIControlStateNormal];
}
}
}
else if (self.selected == NO)
{
for (int i = 0; i < buttonCount; i++)
{
if (self.tag == i)
{
[self setSelected:NO];
[self setImage:[[self selectedImagesArray] objectAtIndex:i] forControlState:UIControlStateNormal];
}
}
}
for (int i = 0; i < buttonCount; i++)
{
if (self.tag != i)
{
[self setSelected:NO];
[self setImage:[[self unselectedImagesArray] objectAtIndex:i] forControlState:UIControlStateNormal];
}
}
}
Thanks for all of the useful information though, figured I should share the final answer I came up with in detail to help anyone else that comes across this problem.
I figured out a pretty easy way to solve this. My example is for 2 buttons but you can easily add more if statements for additional buttons. Connect all buttons to the .h file as properties and name them (I did button1 & button2). Place the following code in your .m file and Connect it (via the storyboard) to all of your buttons. Make sure when you are setting up your button to set an image for BOTH the normal UIControlStateNormal & UIControlStateSelected or this wont work.
- (IBAction)selectedButton1:(id)sender {
if ([sender isSelected]) {
[sender setSelected:NO];
if (sender == self.button1) {
[self.button2 setSelected:YES];
}
if (sender == self.button2) {
[self.button1 setSelected:YES];
}
}
else
{
[sender setSelected:YES];
if (sender == self.button1) {
[self.button2 setSelected:NO];
}
if (sender == self.button2) {
[self.button1 setSelected:NO];
}
}
To answer "It throws a parse error if I have both headers importing each other"...
You should refrain from using #import in .h files as much as possible and instead declare whatever you're wanting to use as a forward class declaration:
#class MyCustomClass
#interface SomethingThatUsesMyCustomClass : UIViewController
#property (nonatomic, strong) MyCustomClass *mcc;
#end
Then #import the header in your .m file:
#import "MyCustomClass.h"
#implementation SomethingThatUsesMyCustomClass
-(MyCustomClass *)mcc
{
// whatever
}
#end
This approach will prevent errors caused by #import cycles.
Though I must say I agree with SergiusGee's comment on the question that this setup feels a bit strange.
The easiest approach here would be to get the parent UIView the buttons are on and iterate through it. Here's a quick example from my code:
for (UIView *tmpButton in bottomBar.subviews)
{
if ([tmpButton isKindOfClass:[UIButton class]])
{
if (tmpButton.tag == 100800)
{
tmpButton.selected = YES;
[tmpButton setTitleColor:[UIColor greenColor] forState:UIControlStateNormal];
[tmpButton setTitleColor:[UIColor greenColor] forState:UIControlStateHighlighted];
}else{
tmpButton.selected = NO;
[tmpButton setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
[tmpButton setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];
}
}
}
Did you try using ReactiveCocoa framework and add some blocks for your code , this is not the most simple approach yet i would say it is the most effective when you have multiple dependencies and very good for scaling
I have created a small project for a solution to your problem using my suggested approach (I tried to adapt it to the good old MVC pattern instead of my preferred MVVM)
you can find it here
https://github.com/MWaly/MWButtonExamples
make sure to install cocoa pods file as we need "ReactiveCocoa" and "BlocksKit" for this sample
we will use two main classes
ViewController => The viewController object displaying the buttons
MWCustomButton => Custom UIButton which handles events
when creating the buttons a weak reference to the viewController is also created using the property
#property (weak) ViewController *ownerViewController ;
events will be handled using the help of blocksKit bk_addEventHandler method and pass it to the block of the ViewController (selectedButtonCallBackBlock)
[button bk_addEventHandler:^(id sender)
{
self.selectedButtonCallBackBlock(button);
} forControlEvents:UIControlEventTouchUpInside];
now in the ViewController for each button touched the callBackButtonBlock will be trigerred , where it will change its currently selected button if applicable
__weak __typeof__(self) weakSelf = self;
self.selectedButtonCallBackBlock=^(MWCustomButton* button){
__typeof__(self) strongSelf = weakSelf;
strongSelf.currentSelectedButton=button;
};
in the MWCustomButton class , it would listen for any changes in the property of "currentSelectedButton" of its ownerViewController and will change its selection property according to it using our good Reactive Cocoa
///Observing changes to the selected button
[[RACObserve(self, ownerViewController.currentSelectedButton) distinctUntilChanged] subscribeNext:^(MWCustomButton *x) {
self.selected=(self==x);
}];
i think this would solve your problem , again your question might be solved in a simpler way , however i believe using this approach would be more scalable and cleaner.
Loop through all views in parent view. Check if it is a UIButton(or your custom button class) and not the sender. Set all views isSelected to false. Once loop is finished, set sender button isSelected to true.
Swift 3 way:
func buttonPressed(sender: UIButton) {
for view in view.subviews {
if view is UIButton && view != sender {
(view as! UIButton).isSelected = false
}
}
sender.isSelected = true
}
Swift 4
//Deselect all tip buttons via IBOutlets
button1.isSelected = false
button2.isSelected = false
button3.isSelected = false
//Make the button that triggered the IBAction selected.
sender.isSelected = true
//Get the current title of the button that was pressed.
let buttonTitle = sender.currentTitle!

UIButton in cell in collection view not receiving touch up inside event

The following code expresses my problem:
(It's self-contained in that you could create a Xcode project with an empty template, replace the contents of the main.m file, delete the AppDelegate.h/.m files and build it)
//
// main.m
// CollectionViewProblem
//
#import <UIKit/UIKit.h>
#interface Cell : UICollectionViewCell
#property (nonatomic, strong) UIButton *button;
#property (nonatomic, strong) UILabel *label;
#end
#implementation Cell
- (id)initWithFrame:(CGRect)frame
{
if (self = [super initWithFrame:frame])
{
self.label = [[UILabel alloc] initWithFrame:self.bounds];
self.label.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
self.label.backgroundColor = [UIColor greenColor];
self.label.textAlignment = NSTextAlignmentCenter;
self.button = [UIButton buttonWithType:UIButtonTypeInfoLight];
self.button.frame = CGRectMake(-frame.size.width/4, -frame.size.width/4, frame.size.width/2, frame.size.width/2);
self.button.backgroundColor = [UIColor redColor];
[self.button addTarget:self action:#selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
[self.contentView addSubview:self.label];
[self.contentView addSubview:self.button];
}
return self;
}
// Overriding this because the button's rect is partially outside the parent-view's bounds:
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
if ([super pointInside:point withEvent:event])
{
NSLog(#"inside cell");
return YES;
}
if ([self.button
pointInside:[self convertPoint:point
toView:self.button] withEvent:nil])
{
NSLog(#"inside button");
return YES;
}
return NO;
}
- (void)buttonClicked:(UIButton *)sender
{
NSLog(#"button clicked!");
}
#end
#interface ViewController : UICollectionViewController
#end
#implementation ViewController
// (1a) viewdidLoad:
- (void)viewDidLoad
{
[super viewDidLoad];
[self.collectionView registerClass:[Cell class] forCellWithReuseIdentifier:#"ID"];
}
// collection view data source methods ////////////////////////////////////
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return 100;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
Cell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"ID" forIndexPath:indexPath];
cell.label.text = [NSString stringWithFormat:#"%d", indexPath.row];
return cell;
}
///////////////////////////////////////////////////////////////////////////
// collection view delegate methods ////////////////////////////////////////
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"cell #%d was selected", indexPath.row);
}
////////////////////////////////////////////////////////////////////////////
#end
#interface AppDelegate : UIResponder <UIApplicationDelegate>
#property (strong, nonatomic) UIWindow *window;
#end
#implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
ViewController *vc = [[ViewController alloc] initWithCollectionViewLayout:layout];
layout.itemSize = CGSizeMake(128, 128);
layout.minimumInteritemSpacing = 64;
layout.minimumLineSpacing = 64;
layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
layout.sectionInset = UIEdgeInsetsMake(32, 32, 32, 32);
self.window.rootViewController = vc;
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
return YES;
}
#end
int main(int argc, char *argv[])
{
#autoreleasepool {
return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
}
}
Basically I'm creating a Springboard-type UI using collection views. My UICollectionViewCell subclass (Cell) has a button which lies partially outside the cell's contentView (i.e. its superview's) bounds.
The problem is that clicking on any part of the button outside of the contentView bounds (basically 3/4th of the button) doesn't invoke the button action. Only when clicking on the portion of the button that overlaps the contentView is the button's action method called.
I've even overridden -pointInside:withEvent: method in Cell so that touches in the button will be acknowledged. But that hasn't helped with the button clicking problem.
I'm guessing it might be something to do with how collectionView handles touches, but I don't know what. I know that UICollectionView is a UIScrollView subclass and I've actually tested that overriding -pointInside:withEvent: on a view (made subview to a scroll view) containing a partially overlapping button solves the button clicking problem, but it hasn't worked here.
Any help?
** Added:
For the record, my current solution to the problem involves insetting a smaller subview to contentView which gives the cell its appearance. The delete button is added to the contentView such that its rect actually lies within the bounds of contentView but only partially overlaps the visible part of the cell (i.e. the inset subview). So I've got the effect I wanted, and the button is working properly. But I'm still curious about the problem with the original implementation above.
The problem appears to be with hitTest/pointInside. I'm guessing the cell is returning NO from pointInside if the touch is on the part of the button that is outside the cell and thus the button doesn't get hit tested. To fix this you have to override pointInside on your UICollectionViewCell subclass to take the button into account. You also need to override hitTest to return the button if the touch is inside the button. Here are example implementations assuming your button is in a property in the UICollectionViewCell subclass called deleteButton.
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
UIView *view = [self.deleteButton hitTest:[self.deleteButton convertPoint:point fromView:self] withEvent:event];
if (view == nil) {
view = [super hitTest:point withEvent:event];
}
return view;
}
-(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
if ([super pointInside:point withEvent:event]) {
return YES;
}
//Check to see if it is within the delete button
return !self.deleteButton.hidden && [self.deleteButton pointInside:[self.deleteButton convertPoint:point fromView:self] withEvent:event];
}
Note that because hitTest and pointInside expect the point to be in the coordinate space of the receiver you have to remember to convert the point before calling those methods on the button.
In Interface Builder do you have set the object as UICollectionViewCell? Because erroneously one time I set a UIView and after assign to it the correct UICollectionViewCell class...but doing this things (buttons, labels, ecc.) are not added tor the contentView so they don't respond as they would...
So, remind in IB to take the UICollectionViewCell Object when drawing the interface :)
Swift version:
override func hitTest(point: CGPoint, withEvent event: UIEvent?) -> UIView? {
//From higher z- order to lower except base view;
for (var i = subviews.count-2; i >= 0 ; i--){
let newPoint = subviews[i].convertPoint(point, fromView: self)
let view = subviews[i].hitTest(newPoint, withEvent: event)
if view != nil{
return view
}
}
return super.hitTest(point, withEvent: event)
}
that's it ... for all subViews
I am successfully receiving touches to a button created as follows in the subclassed UICollectionViewCell.m file;
- (id)initWithCoder:(NSCoder *)aDecoder
{
self = [super initWithCoder:aDecoder];
if (self)
{
// Create button
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.frame = CGRectMake(0, 0, 100, 100); // position in the parent view and set the size of the button
[button setTitle:#"Title" forState:UIControlStateNormal];
[button setImage:[UIImage imageNamed:#"animage.png"] forState:UIControlStateNormal];
[button addTarget:self action:#selector(button:) forControlEvents:UIControlEventTouchUpInside];
// add to contentView
[self.contentView addSubview:button];
}
return self;
}
I added the button in code after realising that buttons added in Storyboard did not work, not sure if this is fixed in latest Xcode.
Hope that helps.
I see two swift conversions of the original answer that aren't exactly swift conversions. So I just want to give the Swift 4 conversion of the original answer so everyone who wants to can use it. You can just paste the code into your subclassed UICollectionViewCell. Just make sure that you change closeButton with your own button.
override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
var view = closeButton.hitTest(closeButton.convert(point, from: self), with: event)
if view == nil {
view = super.hitTest(point, with: event)
}
return view
}
override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
if super.point(inside: point, with: event) {
return true
}
return !closeButton.isHidden && closeButton.point(inside: closeButton.convert(point, from: self), with: event)
}
As accepted answer requested, we should make a hitTest in order to recieve touches inside the cell. Here is the Swift 4 code for hit test:
override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
for i in (0..<subviews.count-1).reversed() {
let newPoint = subviews[i].convert(point, from: self)
if let view = subviews[i].hitTest(newPoint, with: event) {
return view
}
}
return super.hitTest(point, with: event)
}
I had a similar problem trying to place a deletion button outside the bounds of a uicollectionview cell and it didn't seam to respond to tap events.
the way i solved it was to place a UITapGestureRecognizer on the collection and when a tap happend preform the following code
//this works also on taps outside the cell bouns, im guessing by getting the closest cell to the point of click.
NSIndexPath* tappedCellPath = [self.collectionView indexPathForItemAtPoint:[tapRecognizer locationInView:self.collectionView]];
if(tappedCellPath) {
UICollectionViewCell *tappedCell = [self.collectionView cellForItemAtIndexPath:tappedCellPath];
CGPoint tapInCellPoint = [tapRecognizer locationInView:tappedCell];
//if the tap was outside of the cell bounds then its in negative values and it means the delete button was tapped
if (tapInCellPoint.x < 0) [self deleteCell:tappedCell];
}
Honus has the best answer here in my opinion. In fact the only one that worked for me so I've been answering other similar questions and sending them this way:
I spent hours scouring the web for a solution to my UIButton's inside UICollectionView's not working. Driving me nuts until I finally found a solution that works for me. And I believe it's also the proper way to go: hacking the hit tests. It's a solution that can go a lot deeper (pun intended) than fixing the UICollectionView Button issues as well, as it can help you get the click event to any button buried under other views that are blocking your events from getting through:
UIButton in cell in collection view not receiving touch up inside event
Since that SO answer was in Objective C, I followed the clues from there to find a swift solution:
http://khanlou.com/2018/09/hacking-hit-tests/
--
When I would disable user interaction on the cell, or any other variety of answers I tried, nothing worked.
The beauty of the solution I posted above is that you can leave your addTarget's and selector functions how you are used to doing them since they were most likey never the problem. You need only override one function to help the touch event make it to its destination.
Why the solution works:
For the first few hours I figured the gesture wasn't being registered properly with my addTarget calls. It turns out the targets were registering fine. The touch events were simply never reaching my buttons.
The reality seems to be from any number of SO posts and articles I read, that UICollectionView Cells were meant to house one action, not multiple for a variety of reasons. So you were only supposed to be using the built in selection actions. With that in mind, I believe the proper way around this limitation is not to hack UICollectionView to disable certain aspects of scrolling or user interaction. UICollectionView is only doing its job. The proper way is to hack the hit tests to intercept the tap before it gets to UICollectionView and figure out which items they were tapping on. Then you simply send a touch event to the button they were tapping on, and let your normal stuff do the work.
My final solution (from the khanlou.com article) is to put my addTarget declaration and my selector function wherever I like (in the cell class or the cellForItemAt override), and in the cell class overriding the hitTest function.
In my cell class I have:
#objc func didTapMyButton(sender:UIButton!) {
print("Tapped it!")
}
and
override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
guard isUserInteractionEnabled else { return nil }
guard !isHidden else { return nil }
guard alpha >= 0.01 else { return nil }
guard self.point(inside: point, with: event) else { return nil }
// add one of these blocks for each button in our collection view cell we want to actually work
if self.myButton.point(inside: convert(point, to: myButton), with: event) {
return self.myButton
}
return super.hitTest(point, with: event)
}
And in my cell class init I have:
self.myButton.addTarget(self, action: #selector(didTapMyButton), for: .touchUpInside)
I found this from here py4u.net
tried the solution that was at the very bottom. (the whole stuff was collected from this page, as I understand)
In my case the colution also worked. and then I just checked wether the User Interaction Enabled checkmark is checked on Collection view in xib and in it's contentView. Guess what. the contentView`s UserInteraction was disabled.
Enabling it fixed the issue with button's touchUpInside event and there was no need to override hitTest method.
You might not have to override hit test or do any of the complicated solutions above.
This issue can also be caused if you are using a custom button with lots of subviews.
What happens is when the button is hit tested, one of its subviews is being returned.
A cleaner solution here is just to set userInteractionEnabled = false on all of your button's subviews.
That way, hit testing your button will only ever return the button itself and none of the views on it.

iPad undo button (a-la Keynote and other apps)

In Keynote (and other apps), I've noticed the "standard" interface of doing Undo/Redo is by providing an Undo button on the tool bar.
Clicking the button (that is always enabled) Undos the recent operation.
(If there is not recent operation to undo, it will show the Undo/Redo menu).
Long-clicking the Undo button opens an Undo/Redo menu.
I searched for methods of implementing this, and the best answer I found so far is at the following link.
I wonder if anyone knows of a simpler way?
Thanks!
After reviewing all methods and discussing with friends, below is the solution I used, for a UIBarButtonItem the responds to both taps and long-press (TapOrLongPressBarButtonItem).
It is based on the following principals:
Subclass UIBarButtonItem
Use a custom view (so it's really trivial to handle the long-press - since our custom view has no problem responding to a long-press gesture handler...)
... So far - this approach was in the other SO thread - and I didn't like this approach since I couldn't find and easy enough way of making the custom view appear like an iPad navigation bar button... Soooo...
Use UIGlossyButton by Water Lou (thanks water!). This use is encapsulated within the subclass...
The resulting code is as follows:
#protocol TapOrPressButtonDelegate;
#interface TapOrPressBarButtonItem : UIBarButtonItem {
UIGlossyButton* _tapOrPressButton;
__weak id<TapOrPressButtonDelegate> _delegate;
}
- (id)initWithTitle:(NSString*)title andDelegate:(id<TapOrPressButtonDelegate>)delegate;
#end
#protocol TapOrPressButtonDelegate<NSObject>
- (void)buttonTapped:(UIButton*)button withBarButtonItem:(UIBarButtonItem*)barButtonItem;
- (void)buttonLongPressed:(UIButton*)button withBarButtonItem:(UIBarButtonItem*)barButtonItem;
#end
#implementation TapOrPressBarButtonItem
- (void)buttonLongPressed:(UILongPressGestureRecognizer*)gesture {
if (gesture.state != UIGestureRecognizerStateBegan)
return;
if([_delegate respondsToSelector:#selector(buttonLongPressed:withBarButtonItem:)]) {
[_delegate buttonLongPressed:_tapOrPressButton withBarButtonItem:self];
}
}
- (void)buttonTapped:(id)sender {
if (sender != _tapOrPressButton) {
return;
}
if([_delegate respondsToSelector:#selector(buttonTapped:withBarButtonItem:)]) {
[_delegate buttonTapped:_tapOrPressButton withBarButtonItem:self];
}
}
- (id)initWithTitle:(NSString*)title andDelegate:(id<TapOrPressButtonDelegate>)delegate {
if (self = [super init]) {
// Store delegate reference
_delegate = delegate;
// Create the customm button that will have the iPad-nav-bar-default appearance
_tapOrPressButton = [UIGlossyButton buttonWithType:UIButtonTypeCustom];
[_tapOrPressButton setTitle:title forState:UIControlStateNormal];
[_tapOrPressButton setNavigationButtonWithColor:[UIColor colorWithRed:123.0/255 green:130.0/255 blue:139.0/255 alpha:1.0]];
// Calculate width...
CGSize labelSize = CGSizeMake(1000, 30);
labelSize = [title sizeWithFont:_tapOrPressButton.titleLabel.font constrainedToSize:labelSize lineBreakMode:UILineBreakModeMiddleTruncation];
_tapOrPressButton.frame = CGRectMake(0, 0, labelSize.width+20, 30);
// Add a handler for a tap
[_tapOrPressButton addTarget:self action:#selector(buttonTapped:) forControlEvents:UIControlEventTouchUpInside];
// Add a handler for a long-press
UILongPressGestureRecognizer* buttonLongPress_ = [[UILongPressGestureRecognizer alloc] initWithTarget:self
action:#selector(buttonLongPressed:)];
[_tapOrPressButton addGestureRecognizer:buttonLongPress_];
// Set this button as the custom view of the bar item...
self.customView = _tapOrPressButton;
}
return self;
}
// Safe guards...
- (id)initWithImage:(UIImage *)image style:(UIBarButtonItemStyle)style target:(id)target action:(SEL)action {
NSLog(#"%s not supported!", __FUNCTION__);
return nil;
}
- (id)initWithImage:(UIImage *)image landscapeImagePhone:(UIImage *)landscapeImagePhone style:(UIBarButtonItemStyle)style target:(id)target action:(SEL)action {
NSLog(#"%s not supported!", __FUNCTION__);
return nil;
}
- (id)initWithTitle:(NSString *)title style:(UIBarButtonItemStyle)style target:(id)target action:(SEL)action {
NSLog(#"%s not supported!", __FUNCTION__);
return nil;
}
- (id)initWithBarButtonSystemItem:(UIBarButtonSystemItem)systemItem target:(id)target action:(SEL)action {
NSLog(#"%s not supported!", __FUNCTION__);
return nil;
}
- (id)initWithCustomView:(UIView *)customView {
NSLog(#"%s not supported!", __FUNCTION__);
return nil;
}
#end
And all you need to do is:
1. Instantiate is as follows:
TapOrPressBarButtonItem* undoMenuButton = [[TapOrPressBarButtonItem alloc] initWithTitle:NSLocalizedString(#"Undo", #"Undo Menu Title") andDelegate:self];
2. Connect the button to the navigation bar:
[self.navigationItem setLeftBarButtonItem:undoMenuButton animated:NO];
3. Implement the TapOrPressButtonDelegate protocol, and you're done...
-(void)buttonTapped:(UIButton*)button withBarButtonItem:(UIBarButtonItem*)barButtonItem {
[self menuItemUndo:barButtonItem];
}
-(void)buttonLongPressed:(UIButton*)button withBarButtonItem:(UIBarButtonItem*)barButtonItem {
[self undoMenuClicked:barButtonItem];
}
Hope this helps anyone else...
If you are using IB (or in Xcode4 the designer...i guess it is called) then you can select "Undo" from the First responder and drag that action to a button. I can give you more specific instructions if that doesn't cover it.
Here's what it looks like
It's on the left underneath the column "Received actions" at the bottom
I believe the key is actually in the UINavigationBar itself. Unlike UIButtons or other normal touch tracking objects, I suspect UIBarItems don't handle their own touches. They don't inherit UIResponder or UIControl methods. However UINavigationBar of course does. And I've personally added gestures straight to a UINavigationBar many times.
I suggest you override touch handling in a UINavigationBar subclass and check the touches against its children. If the child is your special Undo button you can handle it accordingly.
UIButton* undoButton = [UIButton buttonWithType:UIButtonTypeCustom];
[undoButton addTarget:self action:#selector(undoPressStart:) forControlEvents:UIControlEventTouchDown];
[undoButton addTarget:self action:#selector(undoPressFinish:) forControlEvents:UIControlEventTouchUpInside];
UIBarButtonItem* navButton = [[[UIBarButtonItem alloc] initWithCustomView:undoButton] autorelease];
self.navigationItem.rightBarButtonItem = navButton;
You don't necessarily have to add the UIBarButtonItem as the rightBarButtonItem, this is just and easy way to show you how to create your UIBarButtonItem with a custom view that is the UIButton you want to handle events.
You'll need to implement the undoPressStart: and undoPressFinish: by maintaining state. I'd say on start, store the current NSDate or some granular representation of the time. On finish, if check the time elapsed and if it is beyond a certain threshold, show the menu - otherwise (as well as if the start date was never captured) perform the undo.
As an improvement, you'll likely want to observe the UIControlEventTouchDragExit event as well to cancel the long press.

Passing parameters to addTarget:action:forControlEvents

I am using addTarget:action:forControlEvents like this:
[newsButton addTarget:self
action:#selector(switchToNewsDetails)
forControlEvents:UIControlEventTouchUpInside];
and I would like to pass parameters to my selector "switchToNewsDetails".
The only thing I succeed in doing is to pass the (id)sender by writing:
action:#selector(switchToNewsDetails:)
But I am trying to pass variables like integer values. Writing it this way doesn't work :
int i = 0;
[newsButton addTarget:self
action:#selector(switchToNewsDetails:i)
forControlEvents:UIControlEventTouchUpInside];
Writing it this way does not work either:
int i = 0;
[newsButton addTarget:self
action:#selector(switchToNewsDetails:i:)
forControlEvents:UIControlEventTouchUpInside];
Any help would be appreciated :)
action:#selector(switchToNewsDetails:)
You do not pass parameters to switchToNewsDetails: method here. You just create a selector to make button able to call it when certain action occurs (touch up in your case). Controls can use 3 types of selectors to respond to actions, all of them have predefined meaning of their parameters:
with no parameters
action:#selector(switchToNewsDetails)
with 1 parameter indicating the control that sends the message
action:#selector(switchToNewsDetails:)
With 2 parameters indicating the control that sends the message and the event that triggered the message:
action:#selector(switchToNewsDetails:event:)
It is not clear what exactly you try to do, but considering you want to assign a specific details index to each button you can do the following:
set a tag property to each button equal to required index
in switchToNewsDetails: method you can obtain that index and open appropriate deatails:
- (void)switchToNewsDetails:(UIButton*)sender{
[self openDetails:sender.tag];
// Or place opening logic right here
}
To pass custom params along with the button click you just need to SUBCLASS UIButton.
(ASR is on, so there's no releases in the code.)
This is myButton.h
#import <UIKit/UIKit.h>
#interface myButton : UIButton {
id userData;
}
#property (nonatomic, readwrite, retain) id userData;
#end
This is myButton.m
#import "myButton.h"
#implementation myButton
#synthesize userData;
#end
Usage:
myButton *bt = [myButton buttonWithType:UIButtonTypeCustom];
[bt setFrame:CGRectMake(0,0, 100, 100)];
[bt setExclusiveTouch:NO];
[bt setUserData:**(insert user data here)**];
[bt addTarget:self action:#selector(touchUpHandler:) forControlEvents:UIControlEventTouchUpInside];
[view addSubview:bt];
Recieving function:
- (void) touchUpHandler:(myButton *)sender {
id userData = sender.userData;
}
If you need me to be more specific on any part of the above code — feel free to ask about it in comments.
Need more than just an (int) via .tag? Use KVC!
You can pass any data you want through the button object itself (by accessing CALayers keyValue dict).
Set your target like this (with the ":")
[myButton addTarget:self action:#selector(buttonTap:) forControlEvents:UIControlEventTouchUpInside];
Add your data(s) to the button itself (well the .layer of the button that is) like this:
NSString *dataIWantToPass = #"this is my data";//can be anything, doesn't have to be NSString
[myButton.layer setValue:dataIWantToPass forKey:#"anyKey"];//you can set as many of these as you'd like too!
*Note: The key shouldn't be a default key of a CALayer property, consider adding a unique prefix to all of your keys to avoid any issues arising from key collision.
Then when the button is tapped you can check it like this:
-(void)buttonTap:(UIButton*)sender{
NSString *dataThatWasPassed = (NSString *)[sender.layer valueForKey:#"anyKey"];
NSLog(#"My passed-thru data was: %#", dataThatWasPassed);
}
Target-Action allows three different forms of action selector:
- (void)action
- (void)action:(id)sender
- (void)action:(id)sender forEvent:(UIEvent *)event
I made a solution based in part by the information above. I just set the titlelabel.text to the string I want to pass, and set the titlelabel.hidden = YES
Like this :
UIButton *imageclick = [[UIButton buttonWithType:UIButtonTypeCustom] retain];
imageclick.frame = photoframe;
imageclick.titleLabel.text = [NSString stringWithFormat:#"%#.%#", ti.mediaImage, ti.mediaExtension];
imageclick.titleLabel.hidden = YES;
This way, there is no need for a inheritance or category and there is no memory leak
I was creating several buttons for each phone number in an array so each button needed a different phone number to call. I used the setTag function as I was creating several buttons within a for loop:
for (NSInteger i = 0; i < _phoneNumbers.count; i++) {
UIButton *phoneButton = [[UIButton alloc] initWithFrame:someFrame];
[phoneButton setTitle:_phoneNumbers[i] forState:UIControlStateNormal];
[phoneButton setTag:i];
[phoneButton addTarget:self
action:#selector(call:)
forControlEvents:UIControlEventTouchUpInside];
}
Then in my call: method I used the same for loop and an if statement to pick the correct phone number:
- (void)call:(UIButton *)sender
{
for (NSInteger i = 0; i < _phoneNumbers.count; i++) {
if (sender.tag == i) {
NSString *callString = [NSString stringWithFormat:#"telprompt://%#", _phoneNumbers[i]];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:callString]];
}
}
}
As there are many ways mentioned here for the solution, Except category feature .
Use the category feature to extend defined(built-in) element into your
customisable element.
For instance(ex) :
#interface UIButton (myData)
#property (strong, nonatomic) id btnData;
#end
in the your view Controller.m
#import "UIButton+myAppLists.h"
UIButton *myButton = // btn intialisation....
[myButton set btnData:#"my own Data"];
[myButton addTarget:self action:#selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
Event handler:
-(void)buttonClicked : (UIButton*)sender{
NSLog(#"my Data %#", sender. btnData);
}
You can replace target-action with a closure (block in Objective-C) by adding a helper closure wrapper (ClosureSleeve) and adding it as an associated object to the control so it gets retained. That way you can pass any parameters.
Swift 3
class ClosureSleeve {
let closure: () -> ()
init(attachTo: AnyObject, closure: #escaping () -> ()) {
self.closure = closure
objc_setAssociatedObject(attachTo, "[\(arc4random())]", self, .OBJC_ASSOCIATION_RETAIN)
}
#objc func invoke() {
closure()
}
}
extension UIControl {
func addAction(for controlEvents: UIControlEvents, action: #escaping () -> ()) {
let sleeve = ClosureSleeve(attachTo: self, closure: action)
addTarget(sleeve, action: #selector(ClosureSleeve.invoke), for: controlEvents)
}
}
Usage:
button.addAction(for: .touchUpInside) {
self.switchToNewsDetails(parameter: i)
}
There is another one way, in which you can get indexPath of the cell where your button was pressed:
using usual action selector like:
UIButton *btn = ....;
[btn addTarget:self action:#selector(yourFunction:) forControlEvents:UIControlEventTouchUpInside];
and then in in yourFunction:
- (void) yourFunction:(id)sender {
UIButton *button = sender;
CGPoint center = button.center;
CGPoint rootViewPoint = [button.superview convertPoint:center toView:self.tableView];
NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:rootViewPoint];
//the rest of your code goes here
..
}
since you get an indexPath it becames much simplier.
See my comment above, and I believe you have to use NSInvocation when there is more than one parameter
more information on NSInvocation here
http://cocoawithlove.com/2008/03/construct-nsinvocation-for-any-message.html
This fixed my problem but it crashed unless I changed
action:#selector(switchToNewsDetails:event:)
to
action:#selector(switchToNewsDetails: forEvent:)
I subclassed UIButton in CustomButton and I add a property where I store my data. So I call method: (CustomButton*) sender and in the method I only read my data sender.myproperty.
Example CustomButton:
#interface CustomButton : UIButton
#property(nonatomic, retain) NSString *textShare;
#end
Method action:
+ (void) share: (CustomButton*) sender
{
NSString *text = sender.textShare;
//your work…
}
Assign action
CustomButton *btn = [[CustomButton alloc] initWithFrame: CGRectMake(margin, margin, 60, 60)];
// other setup…
btnWa.textShare = #"my text";
[btn addTarget: self action: #selector(shareWhatsapp:) forControlEvents: UIControlEventTouchUpInside];
If you just want to change the text for the leftBarButtonItem shown by the navigation controller together with the new view, you may change the title of the current view just before calling pushViewController to the wanted text and restore it in the viewHasDisappered callback for future showings of the current view.
This approach keeps the functionality (popViewController) and the appearance of the shown arrow intact.
It works for us at least with iOS 12, built with Xcode 10.1 ...

Resources