Is there a FirstResponder all the time? - ios

If I am currently not having any interaction with the app (no textfield selected etc...), is there still a first responder object? As I tested, if I send a message to the responder chain, then the current ViewController.view receives it, but its isFirstResponder returns with NO. So I am guessing some other element is still first responder? Or there is always a responder chain, but not necessarily a first responder object?

You can find the first responder with this:
#implementation UIView (FindFirstResponder)
- (UIView *)findFirstResponder
{
if (self.isFirstResponder) {
return self;
}
for (UIView *subView in self.subviews) {
UIView *firstResponder = [subView findFirstResponder];
if (firstResponder != nil) {
return firstResponder;
}
}
return nil;
}
#end

The answer:
No, there does not have to be a first responder at all times. You can find routines on git to walk every subview from self.view, looking for the first responder, if you care to:
#implementation UIView (FindFirstResponder)
- (UIView *)findFirstResponder
{
if (self.isFirstResponder) {
return self;
}
for (UIView *subView in self.subviews) {
UIView *firstResponder = [subView findFirstResponder];
if (firstResponder != nil) {
return firstResponder;
}
}
return nil;
}
#end
I tried this, and sometimes it returned with nil as expected. self.view still got the message sent to first responder.

Related

Using UIKeyCommand to map keyboard shortcuts renders UITextField/View useless

I'm using UIKeyCommand to map certain shortcuts (for example "b", arrow keys, "t", "p", etc.) to a functionality inside my UIViewController subclass. The app is kind of a vector graphics software, which allows addition of text objects inside the canvas. The problem arises when a textView or textField inside the view controller is being edited. While it gets the first responder status, it doesn't receive the shortcut keys (for example writing "beaver" will result in "eaver").
Is there a correct way to handle shortcut keys AND use text objects inside a single view controller?
The solution I found to work best is to go through the responder chain to find the active responder and then check whether it is a UITextField/UITextView or something else. In case it is, return nil from the - (NSArray *)keyCommands method, otherwise return the shortcuts.
Here's the code itself:
#implementation UIResponder (CMAdditions)
- (instancetype)cm_activeResponder {
UIResponder *activeResponder = nil;
if (self.isFirstResponder) {
activeResponder = self;
} else if ([self isKindOfClass:[UIViewController class]]) {
if ([(UIViewController *)self parentViewController]) {
activeResponder = [[(UIViewController *)self parentViewController] cm_activeResponder];
}
if (!activeResponder) {
activeResponder = [[(UIViewController *)self view] cm_activeResponder];
}
} else if ([self isKindOfClass:[UIView class]]) {
for (UIView *subview in [(UIView *)self subviews]) {
activeResponder = [subview cm_activeResponder];
if (activeResponder) break;
}
}
return activeResponder;
}
#end
And this goes inside the keyCommands method:
- (NSArray *)keyCommands {
if ([self.cm_activeResponder isKindOfClass:[UITextView class]] || [self.cm_activeResponder isKindOfClass:[UITextField class]]) {
return nil;
}
UIKeyCommand *brushTool = [UIKeyCommand keyCommandWithInput:#"b"
modifierFlags:kNilOptions
action:#selector(brushToolEnabled)
discoverabilityTitle:NSLocalizedString(#"Brush tool", #"Brush tool")];
UIKeyCommand *groupKey = [UIKeyCommand keyCommandWithInput:#"g"
modifierFlags:UIKeyModifierCommand
action:#selector(groupKeyPressed)
discoverabilityTitle:NSLocalizedString(#"Group", #"Group")];
UIKeyCommand *ungroupKey = [UIKeyCommand keyCommandWithInput:#"g"
modifierFlags:UIKeyModifierCommand|UIKeyModifierShift
action:#selector(ungroupKeyPressed)
discoverabilityTitle:NSLocalizedString(#"Ungroup", #"Ungroup")];
return #[groupKey, ungroupKey, brushTool];
}
My solution was to override canPerformAction:withSender: and return false if the the view controller (that has the shortcut keyCommands) is not the first responder. This makes the walk down the responder chain unsuccessful in finding a target that accepts the key command and instead the key press is sent to the first responder as UIKeyInput as normal and the character appears in the text field. e.g.
- (BOOL)canPerformAction:(SEL)action withSender:(id)sender{
if(action == #selector(brushKeyCommand:)){
return self.isFirstResponder;
}
return [super canPerformAction:action withSender:sender];
}

how to disregard touch events in topmost uiview when it is clear and a different uiview can handle them

I have a clear UIView which has gesture recognizers attached to it.
This clear uiview covers the entire super view to allow for the gestures to be invoked from anywhere on it.
Under this clear UIView sit different components such as tables,buttons,collectionview etc.
The clear UIView has no idea what is under it any time.
What I want - if a view which is under the clear uiview can handle a touch event (or any type of gesture) - the clear view should disregard that event - and the event will pass through to the underlying view which could handle it.
I tried
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
but I don't know how to make sure the underlying view can handle it.
-(id)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
id hitView = [super hitTest:point withEvent:event];
if (hitView == self)
{
return nil;
}
else
{
return hitView;
}
}
Add this to your to clear view.
If the hit on clear view means just return nil.
You can override pointInside: withEvent: method. This method returns a boolean value indicating whether the receiver contains the specified point. So if we return NO then your upper clear view will become transparent for touch events and they will be passed to underlying views.
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
// Clear UIView will now respond to touch events if return NO:
return NO;
}
use below code for your case->
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
UIView *hitTestView = [super hitTest:point withEvent:event];
if(hitTestView!=nil){
//check for gesture
if([hitTestView.gestureRecognizers count]>0)
return hitTestView;
//if it is subclass of UIControl like UIButton etc
else if([hitTestView isKindOfClass:[UIControl class]])
return hitTestView;
//if can handle touches
else if([hitTestView respondsToSelector:#selector(touchesBegan:withEvent:)])
return hitTestView;
else
return nil;
}
else{
return self;
}
}
In the above code if the subView which is hitView can anyway handle touch ,we return that object to handle that touch. If there is no such hitTest view, then we return the view itself.
I used some of these suggestions and used the following solution:
I added the gesture recognizer to the bottom most superview in the heirarchy (and not the top most)
Then in that class over rid
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
UIView *v = [super hitTest:point withEvent:event];
// if v is nil then touch wasn't in this view or its subviews
if (v == nil)
{
return nil;
}
// in any case if the topview was hidden than return the default value
if (self.myTopView.hidden)
{
return v;
}
// if the view isn't hidden but the touch returned a control - than we can pass the touch to the control
if ([v isKindOfClass:[UIControl class]])
{
return v;
}
// decide on what threshold to decide is a touch
CGFloat threshHold = 40;
// if the touch wasn't on a control but could initiate a gesture than that view should get the touch
if (v.gestureRecognizers)
{
threshHold = 30;
// return v;
}
// check if the threshold should be bigger
if ([self someCondition])
{
threshHold = 100;
}
// threshold according to its position - this is the dynamic part
if (point.y > (self.myTopView.frame.origin.y - threshold))
{
return self.handleBarView;
}
return v;
}

Using NIAttributedLabel in UITableViewCell

Problem: Using NIAttributedLabel in UITableViewCell with Action(tap, navigate)
adding a link in label
adding label to cell
adding cell to model with action tap
Here is the problem, if I touch the label on the link, it actually does not show the link but act the tap action.
But if I add a UIButton in UITableViewCell in the same way, the action does not happen and the button response when I touch on the button.
So I guess it is the problem with the label.
How can I solve it?
I figured out this finally;
adding function to file NIAttributedLabel.m
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
// never return self. always return the result of [super hitTest..].
// this takes userInteraction state, enabled, alpha values etc. into account
UIView *hitResult = [super hitTest:point withEvent:event];
// don't check for links if the event was handled by one of the subviews
if (hitResult != self) {
return hitResult;
}
if (self.explicitLinkLocations || self.detectedlinkLocations) {
BOOL didHitLink = ([self linkAtPoint:point] != nil);
if (!didHitLink) {
// not catch the touch if it didn't hit a link
return nil;
}
}
return hitResult;
}
remove all [super touch XXXX] functions in all touchXXX;
then, it works!

ViewController moving up - iOS

This following code is to scroll view up. However, it is not shifting up my viewcontoller. I have debugged code and it hits every single line of code , but my view controller. is not shifting up
//DownViewController.m
-(BOOL) textFieldShouldBeginEditing:(UITextField *)textField
{
if (textField == self.hoursTextField) {
[textField resignFirstResponder];
taggy=self.hoursTextField.tag;
}
if (textField ==self.codeTextField) {
[textField resignFirstResponder];
taggy=self.codeTextField.tag;
}
return YES;
}
- (void)keyboardDidShow:(NSNotification *)notification
{
//Assign new frame to your view
sensorViewController =[[SensorsViewController alloc]initWithNibName:#"SensorsViewController" bundle:[NSBundle mainBundle]];
[sensorViewController setTag:taggy];
}
//SensorsViewController.m
-(void)setTag: (int)tag
{
if(tag==1)
{
a=-80;
[self.view setFrame:CGRectMake(0,a,1030,768)];
}
if(tag==2)
{
a=-260;
[self.view setFrame:CGRectMake(0,a,1030,768)];
}
}
Shift the call of setTag method inside viewDidLoad of SensorsViewController.
You are assigning a new value to sensorViewController every time the keyboard shows. That instance that you just assigned isn't onscreen, so of course the one that is onscreen won't be affected. You should keep a reference to the view controller that's already onscreen, maybe with an IBOutlet if you're using a storyboard or nib file.

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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