Sungju's Slow Life

Personal journal

Using single-tap and double-tap in the same view

If you are going to use two similar gestures in a view, it could cause the problem.
For example, in the following code snippet, I tried to use single tap for changing screen mode while double tap is used to toggle bookmark flag.

    [self.svContent addGestureRecognizer:toggleFavoriteTap]; 
    [self.svContent addGestureRecognizer:toggleFullScreenTap];

But, there’s one problem with this. When you double tap it, single tap also gets an effect. So, every time, I do the double tap, it also changes the screen mode.

To solve this problem, you can use ‘requireGesutreRecognizerToFail:’ method as shown in below code snippet.

    [self.svContent addGestureRecognizer:toggleFavoriteTap]; 
    [toggleFullScreenTap requireGestureRecognizerToFail:toggleFavoriteTap];
    [self.svContent addGestureRecognizer:toggleFullScreenTap];

It will wait double tap happens or end with single tap. toggleFullScreenTap will not happen until double tap failed and if double tap has succeed, toggleFullScreenTap won’t get any chance to get called.

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