I'm having a bit of a problem with a UITapGestureRecognizer. I create it this way:
self.userInteractionEnabled = YES;
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleTap:)];
tapRecognizer.cancelsTouchesInView = NO;
tapRecognizer.delaysTouchesBegan = YES;
tapRecognizer.delegate = self;
tapRecognizer.numberOfTapsRequired = 1;
tapRecognizer.numberOfTouchesRequired = 1;
[self addGestureRecognizer:tapRecognizer];
In the header file I also include and implement the shouldReceiveTouch: method like so:
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
return YES;
}
I've looked through countless threads of people with similar problems and can't seem to find a solution. I've heard that if the view you're adding the gesture recognizer has subviews with userInteractionEnabled set to YES, that could possibly interfere with the tap recognition, so I also include this:
for(UIView *subview in self.subviews) {
subview.userInteractionEnabled = NO;
}
Anyone know why the gesture recognizer doesn't work?
Edit:
Here are some details:
I'm adding the UITapGestureRecognizer to a UIView subclass.
I add the gesture recognizer in the subclass' initWithFrame: method.
I've verified that the gesture recognizer is being added by stepping through the portion of the code where it's actually added.
The view controller that contains this view does not have any gesture recognizers attached to it, but does implement touchesBegan, touchesMoved, and touchesEnded. However, according to this question, that the view controller implements those shouldn't affect the gesture recognition of the view.
Edit 2:
I've verified that there are no other views blocking the view with the gesture recognizer from receiving touches. I've also verified that the view is actually being added to the containing view controller's view. It seems like the problem's elsewhere.
Your set up should work, so I would guess that one of two things is happening. You may have forgotten to actually add this view to the ViewController's view, or there maybe another view placed on top of this view which is stealing the touches?
Another possibility causing the problem is that the view on which the UITapGestureRecognizer is added is not big enough, so when you tap on the screen, the touch point is not located in the view's bounds.
Also make sure the UIView is not transparent. Set the background color to e.g. black. This solved the problem for me.
Related
I have many SubViews in my UIView, and many of them have UIButtons in them. One of the subviews- _bottomView (Coordinates- (0,519,320,49)) has an error. It does not recognise the click events on the buttons placed inside it.
I tried placing a UIButton covering the entire _bottomView and the click event from that Button (testButton) is not being recognised either.
I tried adding a tapRecogniser to the code and the tap from every point, EXCEPT the points within the _bottomView are recognised. TapRecogniser Code below
UITapGestureRecognizer *gr = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleGesture:)];
[self.view addGestureRecognizer:gr];
_bottomView.userInteractionEnabled=true;
-(void)handleGesture:(UIGestureRecognizer *)gestureRecognizer {
CGPoint p = [gestureRecognizer locationInView:self.view];
NSLog(#"got a tap in the region i care about");
}
I tried [self.view addSubview:_bottomView]; and that didn't help either. What could be the issue?
If your view is not receiving touches
Make sure that your UIView has userInteractionEnabled set to YES
Make sure that the view is within the bounds of its superview, and the superview is within the bounds of window.You can print the frames of views using NSLog(#"%#",NSStringFromCGRect(view.frame));
Nothing helped. I had to delete the entire View Controller and redo the whole thing. That obviously solved the problem.
I was looking for GestureRecognizer tutorials on the web and saw that most people used for example UIPanGestureRecognizer directly in the view. Is this common practice, if so, why not in the controller?
I generate my views in the controller and have methods that I would need to call, when the gesture is used. How should the delegation method look like, if my gesture recognizer is in the view class, and the method to be called in the controller class?
A simple UIGestureRecognizer implementation, and the most common one in my opinion is as follows:
//this is where you create the view that you want to add the gesture recognizer
UIImageView * imageView = [[UIImageView alloc] initWithFrame:frame];
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] init];
tapRecognizer.numberOfTapsRequired = 1;
[tapRecognizer addTarget:self action:#selector(imageViewTapped:)];
imageView.userInteractionEnabled = YES;
[imageView addGestureRecognizer:tapRecognizer];
After creating the gesture recognizer and adding it to a UIView subclass you can get the taps with the function you pointed above:
- (void)imageViewTapped:(UIGestureRecognizer *)gestureRecognizer
{
if ( gestureRecognizer.state == UIGestureRecognizerStateRecognized )
{
NSLog(#"tap recognized!");
}
}
So basically, you dont need to worry about the controller/view dilemma.
You always add the gesturerecognizer to a view. and when adding the gesture recognizer you add a target function, which you need to implement in the controller class.
P.S This SO Question might clarify in detail of the dilemma you are facing
In one sense, yes, this violate the MVC pattern. As you say, the view shouldn't have anything to do with how to control it, it's a better habit to group such code in another part of the application.
You can drag an gesture into the storyboard(into the view controller),too.Then from the document outline you make an action(in the vc) for that gesture
I want the ability to change how the playback controls are presented while using the new AVPlayerViewController in AVKit. Basically, I want to overide the single finger tap gesture to do something else, and replace that gesture with a double finger tap. I am subclassing AVPlayerViewController to add this functionality.
I can add the double finger tap easily by creating a new UITapGestureRecognizer, but doing so with a single tap does nothing, as the playback controls still appear and my custom gesture method is not called. I assume because the AVPlayerViewController has a gesture with priority that is called instead.
I setup the gestures like normal...
// singleFingerTap: will never fire...
UITapGestureRecognizer *singleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleFingerTap:)];
singleFingerTap.numberOfTouchesRequired = 1;
singleFingerTap.delegate = self;
[self.view addGestureRecognizer:singleFingerTap];
// doubleFingerTap: will work correctly...
UITapGestureRecognizer *doubleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(doubleFingerTap:)];
doubleFingerTap.numberOfTouchesRequired = 2;
doubleFingerTap.delegate = self;
[self.view addGestureRecognizer:doubleFingerTap];
Any thoughts on how to achieve this without accessing private properties? Is it even permitted? I know I can create my own view controller with an instance of AVPlayer and then create my own playback controls, but I'm hoping I can use the lightweight AVKit player here with a few simple modifications.
I've tried looping through the gestures in AVPlayerViewController's view and removing them, but the gestureRecognizers property was empty. Even if I could do this, I wouldn't know how to add back the gesture to display the playback controls on a double finger tap instead of the single finger tap.
Any suggestions would be much appreciated! Especially whether this is possible/allowed or not. Thanks!
EDIT:
I have found a way to explicitly unblock the player's private gesture that was blocking my own gesture.
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
id firstGesture = gestureRecognizer;
id secondGesture = otherGestureRecognizer;
if ([firstGesture isKindOfClass:[UITapGestureRecognizer class]] && [secondGesture isKindOfClass:[UITapGestureRecognizer class]]) {
UITapGestureRecognizer *tapGesture = firstGesture;
UITapGestureRecognizer *otherTapGesture = secondGesture;
if (tapGesture.numberOfTapsRequired == otherTapGesture.numberOfTapsRequired && tapGesture.numberOfTouches == otherTapGesture.numberOfTouches) {
// Disable the single tap that shows the playback controls...
return YES;
}
}
return NO;
}
This effectively prevents the playback controls from appearing on a tap, and my singleTapGesture: fires as expected. However, I now have the issue of getting the playback controls to appear on a different gesture. Is it possible to reroute the private gesture, or simulate the private gesture programmatically?
Why not just check/modify the target/remove the default gesture recognizers first?
You can access them with the standard UIView's gestureRecognizers.
The gestures recognizers may be buried inside a private subview.
Another solution would be to set userInteractionEnabled to NO and add your gesture recognizers to the superview or to a "overlay" transparent view.
I'm somewhat new to iOS programming
I have some code (abridged) that looks like the following
UIView *someSubView = [[UIView alloc] initWithFrame:...];
[self addSubView:someSubView];
[someSubView addTarget:self action:#selector(_handleTapOnView:) forControlEvents:UIControlEventTouchUpInside];
_tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(_handleTap:)];
_tapGestureRecognizer.delegate = self;
[self.view addGestureRecognizer:_tapGestureRecognizer];
Unfortunately the gesture recognizer triggers and my views addTarget call does not. I've tried commenting out the gesture recognizer code and it works, so I know its not the call to addTarget on the subview.
I solved this initially by using the gestureRecognizer:shouldReceiveTouch: and doing a hit test for the sub view, but I feel like I'm missing some fundamental understanding here that wouldn't require me adding a manual hit test.
Its important to note that I don't want the code in the _handleTap in the _tapGestureRecognizer to execute when I have tapped on my subview.
Any guidance here? Thanks!
Try using:
_tapGestureRecognizer.cancelsTouchesInView = NO;
otherwise the gesture recogniser will intercept the touches and will not forward them further (in other words, the gesture recogniser gets the touch, handles it, and since it cancel it, no other object gets the touch). By not cancelling, the touch is forwarded for any other object (recognisers or views) to handle it.
Newbie question.
In IB I added UIImageView to scene and set few gestures for it in -viewDidLoad this way:
image.userInteractionEnabled = YES;
image.multipleTouchEnabled = YES;
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(controlPan:)];
[image addGestureRecognizer:pan];
pan.delegate = self;
// and few others gestures same way
...
and gestures worked fine. After that in IB I added UIView to the same scene and implement gestures absolutely identically to previous code, again in -viewDidLoad. But after that gestures stop working for both UIView and UIImageView. Do I need to make .h and .m for this view and to implement gesture recognizers there, or reason can be in something else?
If you have same handler method you need to make distinction from which object gesture came, so you can properly handle action. If you set different handler methods for every object you dont have to care from which object gesture was invoked.