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

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.

Answer 2

Yo can also do:

gestureRecognizer.delegate = self

somewhere. generally on viewDidLoad(). then you implement the method:

 func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
        let view = self.getTheViewDontWannaConsider() /* or whateva */

        let point = touch.location(in:view)
        if point.y >= 50 /* or whateva calc. you want */ {
           return false
        }
        return true
    }