CODEWITHSUNDEEP
iosuitapgesturerecognizer
wangshaoping
wangshaoping

Reputation: 83

iOS distinguish single tap and double tap at first opening

I know that I can use requireGestureRecognizerToFail function to distinguish single tap and double tap, but I meet a tiny problem, and I want to fix it. My code is as below:

- (IBAction)singleTap:(UITapGestureRecognizer *)sender {
    NSLOGD_METADATAONLY();
    hideNavigationBar();
    hideStatusBar();
    [sender requireGestureRecognizerToFail:self.doubleTapRecognizer];
}

- (IBAction)doubleTap:(UITapGestureRecognizer *)sender {
    NSLOGD_METADATAONLY();
    //TODO
}

When I open a file and double tap(action1), single tap(result1) will be called firstly and then double tap(result2) will be called.

But if I open a file and single tap(action3), then double tap(action4), the result of action4 is working well,single tap will not be called only double tap will be called. I guess it is because in action3 the function requireGestureRecognizerToFail is called.

My question is HOW CAN I make action1 just call result2 and not call result1?

Upvotes: 1

Views: 751

Answers (3)

Lal Krishna
Lal Krishna

Reputation: 16190

Update your code with [singleTapRecognizer requireGestureRecognizerToFail: doubleTapRecognizer] when you creating UITapGestureRecognizer

Example:

    // single tap    
    UITapGestureRecognizer *singleTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget: tableViewController action: @selector(handleSingleTapOnView:)];                                 
    [singleTapRecognizer setNumberOfTouchesRequired:1];
    [singleTapRecognizer requireGestureRecognizerToFail:doubleTapRecognizer];
    [view addGestureRecognizer: singleTapRecognizer];

    // double tap 
    UITapGestureRecognizer *doubleTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget: tableViewController action: @selector (handleDoubleTapOnView:)];        
    [doubleTapRecognizer setNumberOfTouchesRequired:2];         
    [view addGestureRecognizer: doubleTapRecognizer];

When you set requireGestureRecognizerToFail: for a gesture recognizer, you're saying that it should only recognize the gesture if the other gesture recognizer did not.

Upvotes: 0

luckyShubhra
luckyShubhra

Reputation: 2751

Extend your class as UIGestureRecognizerDelegate.

class ViewController: UIViewController, UIGestureRecognizerDelegate {

Then assign your view controller as delegate of gesture recognizer.

tapGesture .delegate = self;
doubleTapGesture .delegate = self;

Implementation of shouldRequireFailureOf prevents the one gesture from being recognized until after the other gesture recognizer explicitly reaches the failed state.

You need to recognize a single tap only after the failure of a double tap, which happens when the touch sequence contains only one tap. This can be achieved implementing following.

   func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer,
                   shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
// Don't recognize a single tap until a double-tap fails.
       if gestureRecognizer == self.tapGesture &&
            otherGestureRecognizer == self.doubleTapGesture {
          return true
        }
    return false
  }

Hope it helps.Happy Coding!!

Upvotes: 0

Vignesh Davins
Vignesh Davins

Reputation: 285

Write the below lines in ViewDidLoad
[singleTap requireGestureRecognizerToFail:doubleTap];

Upvotes: 1

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