UIGestureRecognizer for part of a UIView

Question

I'm using UIGestureRecognizer in my iOS application and I'm having some issues.

I only want the gestures to work in a certain area of the view, so I made a new UIView with a specific frame and added it to the root view. The gestures are working fine with this, but the only issue now is that I can't click the stuff that is under/behind that new view (the objects that are on the root view). If I set userInteractionEnabled to NO, it breaks the gestures so that is not an option.

What can I do to fix that?

Thanks.

Answer 1

Don't create a new view for your gesture recognizer. The recognizer implements a locationInView: method. Set it up for the view that contains the sensitive region. On the handleGesture, hit-test the region you care about like this:

0) Do all this on the view that contains the region you care about. Don't add a special view just for the gesture recognizer.

1) Setup mySensitiveRect

@property (assign, nonatomic) CGRect mySensitiveRect;
@synthesize mySensitiveRect=_mySensitiveRect;
self.mySensitiveRect = CGRectMake(0.0, 240.0, 320.0, 240.0);

2) Create your gestureRecognizer:

gr = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleGesture:)];
[self.view addGestureRecognizer:gr];
// if not using ARC, you should [gr release];
// mySensitiveRect coords are in the coordinate system of self.view


- (void)handleGesture:(UIGestureRecognizer *)gestureRecognizer {
    CGPoint p = [gestureRecognizer locationInView:self.view];
    if (CGRectContainsPoint(mySensitiveRect, p)) {
        NSLog(@"got a tap in the region i care about");
    } else {
        NSLog(@"got a tap, but not where i need it");
    }
}

The sensitive rect should be initialized in myView's coordinate system, the same view to which you attach the recognizer.