Handling a gesture that needs to address multiple selectors? - ios

Im dealing with some very confusing code on a project, it seems a gesture was used to trigger a func, and that func fires off a selector to a parent view the trigger a func, this is working fine after some tweaks.
Issue is, the subclass is used in a couple of different parent views, so using superview to find a selector is causing a crash, it exists in 1 use, but not in the second.
How can i handle this so that it calls different selectors based on its parent view? The current setup seems pretty hacky and obviously doesnt work as it needs to... some code below:
The reused view inits with this gesture:
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(bandBypassWasPressed:)];
[tap setDelegate:self];
[tap setCancelsTouchesInView:NO];
[self addGestureRecognizer:tap];
Calling this func in its self:
- (IBAction)bandBypassWasPressed:(UITapGestureRecognizer *)sender {
if (CGRectContainsPoint(self.bounds, [sender locationInView:self])) {
[self.superview performSelector:#selector(bandViewOn:) withObject:self];
[self setNeedsDisplay];
}
}
The issue is that 'bandViewOn' only exists in the superview in 1 use of this subview, not in the other, meaning it fires off a call and crashes the app as there isnt a func there with that name.
There is a different func I want it to call depending on its superview. This is
- (void)lowBandBypass:(NSInteger)on {
NSLog(#"lowBandBypass CALLED");
_eqData.filter[1].bypass = on;
_lowBand.on = on;
[_lowBand setNeedsDisplay];
}
How can i handle this to resolve this odd issue...
Cheers and appreciate its a bit complex!

You can use respondsToSelector to check that the superview implements the method before calling it.
if (CGRectContainsPoint(self.bounds, [sender locationInView:self])) {
if [self.superview respondsToSelector:#selector(bandViewOn:)] {
[self.superview performSelector:#selector(bandViewOn:) withObject:self];
}
[self setNeedsDisplay];
}

Related

IBAction not fired sometimes after UIGestureRecognizer handler

I'm trying to track hits on UI elements (tap and long press) using UIGestureRecognizer. After hit was tracked (let's say logged via NSLog) UI element should do it's job.
I'm creating gesture recognizers like this:
UITapGestureRecognizer* tap = [[UITapGestureRecognizer] alloc initWithTarget:self action:(OnGesture:)]
tap.cancelsTouchesInView = NO;
tap.delegate = self;
[view addGestureRecognizer:tap];
UILongPressGestureRecognizer* longPress = [[UILongPressGestureRecognizer] alloc initWithTarget:self action:(OnGesture:)]
longPress.cancelsTouchesInView = NO;
longPress.delegate = self;
[view addGestureRecognizer:longPress];
I've overridden some gesture recognizer methods:
-(BOOL)gestureRecognizer:(UIGestureRecognizer*)_recognizer shouldReceiveTouch(UITouch*)_touch
{
return YES;
}
-(BOOL)gestureRecognizer:(UIGestureRecognizer*)_recognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer*)_otherRecognizer
{
return YES;
}
Inside the gesture recognizer handler, I'm trying to find the exact subview of the tap by using the hitTest method.
-(void)OnGesture:(UIGestureRecognizer*)_recognizer
{
if([_recognizer.state == UIGestureRecognizerStateEnded])
{
if([_recognizer isKindOfClass:[UITapGestureRecognizer class]]
|| [_recognizer isKindOfClass:[UILongPressGestureRecognizer class])
{
CGPoint location = [_recognizer locationOfTouch:0 inView:_recognizer.view];
// my problem occurs here:
//---------------------------------------------------------------------------
UIView* hitView = [_recognizer.view hitTest:location withEvent:nil];
//---------------------------------------------------------------------------
NSLog(#"Hit on view: %#", hitView);
}
}
}
So my problem is:
Sometimes (1 out of 10 cases) when I press the UIButton OnGesture method fires, but the IBAction of the "Touch Up Inside" event of that button is not firing.
But when I comment out hitTest call:
//UIView* hitView = [_recognizer.view hitTest:location withEvent:nil];
the bug stops being reproducible. IBAction always gets called.
Why is this happening? How can I fix this?
P.S. there could be some typos in the sample code above.
According to the docs, in order for it to work:
This method ignores view objects that are hidden, that have disabled user interactions, or have an alpha level less than 0.01. This method does not take the view’s content into account when determining a hit. Thus, a view can still be returned even if the specified point is in a transparent portion of that view’s content.
So you might wanna do self.someSubview.userInteractionEnabled = YES;

Button calc stopped working

I have a simple program that does a calculation on a button press. The result is placed into a label using the following code:
//converts the float to 2 descimal places then converts it to a string
NSString *stringRectResult=[[NSString alloc]
initWithFormat:#"%1.2f",floatCalcResult];
//displays the string result in the label
resultLabel.text=stringRectResult;
It works perfectly, however, I added in code to hide the decimal keyboard when the user touches off the keyboard. That works, but when I added this code the button to update the label no longer worked. Can anyone help? The code to hide the keyboard is below. The app works when I comment it out but does not when it is active
In viewDidLoad:
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc]
initWithTarget:self action:#selector(tap:)];
[self.view addGestureRecognizer:tapRecognizer];
Tap selector...
-(void)tap:(UIGestureRecognizer *)gr
{
[self.view endEditing:YES];
}
Thanks for any and all help.
The problem is that by intercepting all of the user's taps (in order to hide the keyboard), you're preventing any other user interface elements from being tapped. I would urge you to rethink your design; it's not usually necessary to have an explicit facility to hide the keyboard.
If you do want to keep this design, you can implement the gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer: method in your class:
- (void) viewDidLoad
{
// ...
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc]
initWithTarget:self action:#selector(tap:)];
tapRecognizer.delegate = self;
[self.view addGestureRecognizer:tapRecognizer];
}
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}
Two things to keep in mind:
You need to mark your view controller as conforming to the UIGestureRecognizerDelegate protocol.
If you later add a second gesture recognizer to the view, you'll need to add a check inside the second method to treat the second recognizer differently.

how to make an object move by touching it in iOS

I am a newbie in Objective-C and trying to make a simple app in which when you touch the object it will move randomly for a while and stops. then you need to touch it again so it will move again and stop after a while.
I have searched for touch method and some tutorials, but the problem is I don't know how to start. It is like I need a function to move the object and one to touch it, but I don't know how to connect them and use them.
here is a tutorial which helped me a lot to get a view of functionality and it actually function in opposite way of my app. but still I can not start programming on my own.
http://xcodenoobies.blogspot.se/2010/11/under-construction.html
Any help would be appreciated, regarding how to program my logic and how to find the right methods and how to find the type of variables I need.
Step 1: Put this code in your ViewDidLoad Method, in which i have created some UIImageView and add it to View Randomly
[self.view setTag:1];
for(int i=0;i<4;i++)
{
int x = arc4random()%300;
int y = arc4random()%400;
#warning set Image here
UIImageView *imgview = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"someImage.png"]];
[imgview setFrame:CGRectMake(x, y, 25, 25)];
[imgview setUserInteractionEnabled:YES];
[self.view addSubview:imgview];
}
Step 2 : Define touchBegan Method to handle touch and move objects around the view, we have set Tag = 1 for ViewController ,because we dont want to move our mainview, only subviews will be moved
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
if([[touch view] tag] != 1)
{
[UIView animateWithDuration:0.25f animations:^{
int x = arc4random()%300;
int y = arc4random()%400;
[[touch view] setCenter:CGPointMake(x, y)];
}];
}
}
What you need is to add a gesture recognizer to the view you want to be able to touch:
// In a view controller or in a UIView subclass
UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleTap:)];
[self addGestureRecognizer:tapGestureRecognizer];
// Or [self.view addGestureRecognizer:tapGestureRecognizer];
- (void)handleTap:(UITapGestureRecognizer *)sender
{
if (sender.state == UIGestureRecognizerStateEnded) {
// Animate the view, move it around for a while etc.
// For animating a view use animateWithDuration:animations:
}
}
If I get you correctly I would say that the easiest way to achieve what you request is to create a UIButton in Interface Builder and connect it to an IBAction which moves it to a random spot.. You can then add a custom graphic to the button..
Create a public method in your ViewController with return type IBAction
Create a button in IB and connect its "Touch Up Inside" outlet to your IBAction
I your IBAction method, generate a random x and y coordinate within the screens bounds and animate the movement to this point.
I will/can not go into details on the specific code since it would take way to much space.
Note that your question is very open and vague which is not considered good style on StackOverflow. Also, you might wan't to save stuff like animations until you are a bit more experienced with iOS and Objective-C
-V
Actually Apple made a demo for this.
http://developer.apple.com/library/ios/#samplecode/MoveMe/Introduction/Intro.html
You can try to modify this code to your needs. And the actual functions you where looking for where:
- (void) touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event
- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
- (void) touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event
If this is the answer you where looking for please click "answered" so this question can be considered as closed :-).
(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
is a method called when user touches the view. if you override this in mainview (big view) you will have to find if touched point is where the object is with some helper method as described in your link. else you can override your object's class & implement the method so you dont have to explicitly find if touched point is on the object or not.
for your requirement. i'd say override the uiimageview & inside that put the touchesbegan implementation it will just work fine.
.h file
#interface StarView : UIImageView
#end
.m file
#implementation StarView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
// your code in the link with the related methods
Destination = CGPointMake(arc4random() % 320, arc4random() % 480);
// calculate steps based on speed specified and distance between the current location of the sprite and the new destination
xamt = ((Destination.x - self.center.x) / speed);
yamt = ((Destination.y - self.center.y) / speed);
// ask timer to execute moveBall repeatedly each 0.2 seconds. Execute the timer.
mainTimer = [NSTimer scheduledTimerWithTimeInterval:(0.02) target:self selector:#selector(moveBall) userInfo:nil repeats: NO];
}
dont forget to copy the moveBall method after this.
In your mainview just make an instance of StarView & add to mainview

UIButton function with target nil doens´t get called?

i´ve made lots of my own "CustomUIButton" in a for-loop in my viewcontroller.
In this "CustomUIButton"-class i´ve implemented an UIGestureRecognizer like this:
(id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// custom things.
UILongPressGestureRecognizer* longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(handleLongPress:)];
longPress.minimumPressDuration = 1.0;
[self addGestureRecognizer:longPress];
[longPress release];
}
}
- (void) handleLongPress:(UILongPressGestureRecognizer*) recognizer{
if (recognizer.state == UIGestureRecognizerStateEnded) {
NSLog(#"Long press Ended");
}
else {
NSLog(#"Long press detected.");
// Do something
}
}
If i init the target with "self", my "handleLongPress"-function in this class will be called. It´s cool. If i init the target with "nil", it should check the parent viewcontroller, right?
Any ideas why an additional function with the same name in my viewcontroller won´t be called? (For this test i´ve commented the "longpress"-function of the button-class out.)
In the docs for UIGestureRecognizer's initWithTarget:action: method, for the target parameter it says:
An object that is the recipient of
action messages sent by the receiver
when it recognizes a gesture. nil is
not a valid value.
Note the last sentence.
The docs also say this which should explain why it doesn't work:
A gesture recognizer does not
participate in the view’s responder
chain.
You must specify a value for target.

Objective-C, how to Generally resignFirstResponder?

(my boss says) that I have to implement a "Done" button on a navBar so that the various items in the view (that contain an edit box) will dismiss their keyboard (if they were in focus).
It seems that I must iterate through all items and then call resignFirstResponder on each on the off-chance that one of them is in focus? This seems a bit messy (and hard to maintain if e.g. someone else adds more items in future) - is there a better way to do it?
I have found it!
Thanks to this
I discovered that all I need do is this:-
-(void) done {
[[self.tableView superview] endEditing:YES];
}
// also [self.view endEditing:YES]; works fine
[remark]
Also I learn how to do the equivalent of an "eventFilter" to stop UITableViewController from swallowing background touch events by intercepting them before they get there - from the same, wonderful post on that thread - see "DismissableUITableView".
[end of remark]
You don't have to iterate through the controls since only one can be first responder at the moment.
This will reset the responder to the Window itself:
[[self window] makeFirstResponder:nil]
One solution is to use a currentTextField Object,
In .h file have an instance variable as
UITextField *currentTextField;
Now in .m file.
Note : Dont forget to set the delegates of all the textField to this class
- (void)textViewDidBeginEditing:(UITextView *)textView
{
currentTextField = textField;
}
- (void)textViewDidEndEditing:(UITextView *)textView
{
currentTextField = nil;
}
Now in your button action method
-(IBAction)buttonTap
{
if([currentTextField isFirstResponder])
[currentTextField resignFirstResponder];
}
This avoids iterating through all the text field.
I think best way to handle it by searching all subviews of main view with recursive function, check example below
- (BOOL)findAndResignFirstResponder {
if (self.isFirstResponder) {
[self resignFirstResponder];
return YES;
}
for (UIView *subView in self.subviews) {
if ([subView findAndResignFirstResponder]) {
return YES;
}
}
return NO;
}
and also you can put this method to your utility class and can use from tap gesture. All you have to do is simply adding to gesture to view.
UITapGestureRecognizer *gestureRecognizer = [[UITapGestureRecognizer alloc]
initWithTarget:self action:#selector(hideEverything)];
[self.tableView addGestureRecognizer:gestureRecognizer];
and than you can call hideEverything method;
- (void) hideKeyboard {
[self.view findAndResignFirstResponder];
...
...
}

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