在父视图上双击手势，在子视图上单击手势

Question

I have a double tap UITapGestureRecognizer on a view and a single tap UITapGestureRecognizer on it's child view.

    let parentGR = UITapGestureRecognizer(target: self, action: "doubleTappedParent")
    parentGR.numberOfTapsRequired = 2
    parentView.addGestureRecognizer(parentGR)

    let childGR = UITapGestureRecognizer(target: self, action: "singleTappedChild")
    childGR.numberOfTapsRequired = 1
    childView.addGestureRecognizer(childGR)

When I double tap the child view, both actions are triggered. How can I have it such that the single tap gesture "cancels" the double tap gesture?

Answer 1

Create a relationship between recognizers using requireGestureRecognizerToFail . For instance:

gr2.requireGestureRecognizerToFail(gr)

Update: as @tumber033 mentioned in the comment, in his example gr2 and gr should be swapped, so that there should be

parentGR.requireGestureRecognizerToFail(childGR)