Can we add single gesture on multiple views and ma

Question

This question already has an answer here:

• Can you attach a UIGestureRecognizer to multiple views? 10 answers

I am working on a sample of Pan Gesture. I am keen to know that can I add single gesture on two views?

My code is as follows:

UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(invokePanGesture:)];
[panGesture setMinimumNumberOfTouches:1];
[panGesture setMaximumNumberOfTouches:2];

[btnGreen addGestureRecognizer:panGesture];
[btnYellow addGestureRecognizer:panGesture];

my handler method is as follows:

- (void)invokePanGesture:(UIPanGestureRecognizer*)recognizer {
CGPoint translation = [recognizer translationInView:self.view];
recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, 
                                     recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}

The problem now is gesture recognizer is considering only last view in my case btnYellow as its view. If I create two separate GestureRecognizer object it works. So please clear me that:

1. Is it possible to have single gesture in multiple views or not?

2. If yes then how?

3. If now then why?

Thanks in Advance

Answer 1

Can't you just write your invokePanGesture method to do the same thing to both views at the same time?

Answer 2

I don't think it's possible.

Please have a look at https://stackoverflow.com/a/5567684/470964.

Also https://stackoverflow.com/a/7883902/470964: Maybe it's also a solution for your problem. I think the answer is that the GestureRecognizer has only one view property, that will be set.

Answer 3

From the docs for UIGestureRecognizer

A gesture recognizer operates on touches hit-tested to a specific view and all of that view’s subviews. It thus must be associated with that view. To make that association you must call the UIView method addGestureRecognizer:. A gesture recognizer does not participate in the view’s responder chain.

So, in summary the only way a GestureRecognizer can operate on more than one view is if the recognizer operates on a superview of the other views.