Allow both single tap gesture recognizer and double tap in UIScrollView - ios

Question

So I have an UIImageView inside of a UIScrollView, I need to capture both:
- single tap gesture
- double tap gesture
for the UIImageView
The double tap gesture is supposed to be sent to the UIScrollView as an action of zooming
The single tap gesture is captured by a UITapGestureRecognizer that I created myself.
The double tap gesture has higher priority than the single tap (when there is a double tap, zoom in the scrollview, else perform the single tap)
So far if I add the single tap gesture recognizer to the scrollview, the single tap is immediately recognized and no double tap can be recognized.
If I add the single tap gesture recognizer to the imageview, it never receives any action, but double tap works
Any suggestion is appreciated, thanks..

Answer 1

try this code,
Objective - C
UITapGestureRecognizer *singletap = [[UITapGestureRecognizer alloc]
initWithTarget:self
action:#selector(singleTap:)];
singletap.numberOfTapsRequired = 1;
singletap.numberOfTouchesRequired = 1;
[scrollView addGestureRecognizer:singletap];
UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc]
initWithTarget:self
action:#selector(doubleTap:)];
doubleTap.numberOfTapsRequired =2 ;
doubleTap.numberOfTouchesRequired = 1;
[scrollView addGestureRecognizer:doubleTap];
[singleTap requireGestureRecognizerToFail:doubleTap];
Swift 3.0
var singletap = UITapGestureRecognizer(target: self, action: #selector(self.singleTap))
singletap.numberOfTapsRequired = 1
singletap.numberOfTouchesRequired = 1
scrollView.addGestureRecognizer(singletap)
var doubleTap = UITapGestureRecognizer(target: self, action: #selector(self.doubleTap))
doubleTap.numberOfTapsRequired = 2
doubleTap.numberOfTouchesRequired = 1
scrollView.addGestureRecognizer(doubleTap)
singleTap.require(toFail: doubleTap)

Answer 2

UITapGestureRecognizer *tapRecognizerForSingleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTapAction:)];
[tapRecognizerForSingleTap setNumberOfTapsRequired:1];
UITapGestureRecognizer *tapRecognizerForDoubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(doubleTapAction:)];
[tapRecognizerForDoubleTap setNumberOfTapsRequired:2];
Both are added in a same image view and to achieve what you want just add the below line.
[tapRecognizerForSingleTap requireGestureRecognizerToFail:tapRecognizerForDoubleTap];
By the above line you are asking for single tap will be only recognise if it's not double tap.