问题
I want to create a totally transparent UIView overlay (and it has subviews) to receives touches. I could set the alpha to a low value (like 0.02) to get an approximate effect.
But I wonder is it possible for a alpha == 0 UIView to receives touches, through other UIView configs?
回答1:
You can accomplish this by overriding the hitTest:withEvent: method in the class of your fully transparent view, like:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
return self;
}
The implementation of hitTest:withEvent: doesn't have to be that simple, of course. The point is that you can cause even a fully transparent view to be touchable as long as something returns that view from hitTest:withEvent:.
Do note, however, that screwing around with hitTest:withEvent: is an easy way to create some very weird bugs. Use this method with caution.
回答2:
The better way to do this is to set the background colour:
UIView *view = ...;
view.backgroundColor = [UIColor clearColor];
Add a UITapGestureRecognizer to this to hook up a selector to respond to tapping.
来源：https://stackoverflow.com/questions/17083102/can-i-create-a-totally-transparent-uiview-that-receives-touches