objective c - How to compare the types of gestures on iOS?

Question

I have three different gestures with two different types on one view.

First is a UITapGestureRecognizer and the two others are UILongPressGestureRecognizer.

The long press gesture recognizer have different minimumPressDuration, one is 0.15 and the other is 0.50, so to I implemented he following function so that all the gestures are recognized:

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer: (UIGestureRecognizer *) otherGestureRecognizer{
    return true;
}

The function does allow all the gestures to be recognized but the problem is whenever a UILongPressGestureRecognizer is recognized, a UITapGestureRecognizer is also recognized.

So, I want to know how can I compare the types of gestureRecognizer in

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer: (UIGestureRecognizer *) otherGestureRecognizer

or how to stop the UITapGestureRecognizer when UILongPressGestureRecognizer is detected because UITapGestureRecognizer is triggered whenever UILongPressGestureRecognizer is triggered.

Answer 1

Instead of returning YES to all cases in shouldRecognizeSimultaneouslyWithGestureRecognizer:, if you don't want the gestures to be recognized simultaneously, you should actually return NO:

- (BOOL) gestureRecognizer: (UIGestureRecognize *) gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer: (UIGestureRecognizer *) otherGestureRecognizer {
   return NO;
}

But to accomplish what you're apparently trying to accomplish, I'd recommend using a different UIGestureRecognizerDelegate method instead -- gestureRecognizer:shouldBeRequiredToFailByGestureRecognizer: -- so that you can specify which gesture is recognized before the other. In this case, since you'd like to stop the UITapGestureRecognizer when a UILongPressGestureRecognizer is detected, try this:

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {

    // If the gesture recognizer is a UITapGestureRecongizer, but the other
    // gesture detected is a UILongPressGestureRecognizer, require the
    // UITapGestureRecognizer to fail.
    if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]] &&
        [otherGestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]]) {
       return YES;
    } else {
       return NO;
    }
}