UITapGestureRecognizer not working on simulator

Question

Just started iOS programming, trying to get UITapGestureRecognizer working using iOS 5.1 simulator, and i can't seem to get the right values when tapping. here's my code that i took from nathan eror's answer to nathan eror's How to add a touch event to a UIView?

- (void)handleSingleTap:(UITapGestureRecognizer *)recognizer {
    CGPoint location = [recognizer locationInView:[recognizer.view superview]];

    NSLog(@"touched points: %g, %g", location.x, location.y);
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.view.backgroundColor = [UIColor blackColor];
    NSLog(@"gets in here");
    UITapGestureRecognizer *singleFingerTap =
    [[UITapGestureRecognizer alloc] initWithTarget:self
                                            action:@selector(handleSingleTap:)];
    [self.view addGestureRecognizer:singleFingerTap];
}

and i keep getting 0.000000 for my values every time i tap on the trackpad on my macbook pro on the simulator. is it because of the simulator? or am i doig something morbidly wrong?

P.S does anyone know how to highlight the code as objective-C in posting this question? thnx in advance

When you say "tap on the trackpad", do you actually mean _click_, or really _tap_? A click on the simulator window gets treated as a tap inside the simulator. Taps on the physical trackpad have no significance to the simulator -- they don't get passed on, AFAIK. — jscs, Aug 08 '12 at 05:49
@DavidT The site will automatically highlight your code as Objective-C if your question is tagged Objective-C. However, the editor preview usually doesn't highlight in real-time. — rob mayoff, Aug 08 '12 at 05:52
@W'rkncacnter gotcha. umm... i guess more like "click" on the trackpad. so it was simulating the "tap" on simulator — David T., Aug 08 '12 at 06:57

score 2 · Answer 1 · answered Aug 08 '12 at 06:05

I can reproduce your problem. It appears to happen because [recognizer.view superview] is the window (class UIWindow). Although UIWindow is a subclass of UIView, the gesture recognizer doesn't seem to convert the location to the window's coordinate system correctly. If I add a subview to self.view and put the gesture recognizer on that subview, it converts the point to self.view's coordinate system correctly.

I suggest you file a bug report at http://bugreport.apple.com. (The product is “iPhone SDK”.)

If you really need to get the point in the window's coordinate system, you can do this:

- (void)handleSingleTap:(UITapGestureRecognizer *)recognizer {
    CGPoint location = [recognizer locationInView:recognizer.view];
    location = [recognizer.view convertPoint:location toView:recognizer.view.superview];

    NSLog(@"touched point: %g, %g", location.x, location.y);
}

However, the window's coordinate system includes space for the status bar, and doesn't rotate when you rotate the device. It's probably not what you want.

score 0 · Answer 2 · answered Aug 08 '12 at 05:55

0

Try NSLog(@"touched point %@", NSStringFromCGPoint(location))

answered Aug 08 '12 at 05:55

Bernd Rabe

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UITapGestureRecognizer not working on simulator

2 Answers2