UIImageView pixel-perfect `touches began` for non-transparent parts of UIImage

Question

developing iphone app, I have used a UIImageview and i have set an image of irregular shape

// uiimageview type shutter
shutter = [[UIImageView alloc] initWithFrame:CGRectMake(0,0,320,32.5)];

//setting image on shutter
UIImage* shutterimg = [UIImage imageNamed:@"trayshutter.png"];
[shutter setImage:shutterimg];
// User interaction
shutter.userInteractionEnabled=YES;

and i get touches using touchesbegan

everything is fine, but issue is I also get events in all the rectangle area occupied by the CGRectMake (i.e. 0,0,320,32.5) of imageview, whereas i require events only on the image (which is of shape of -----|||||-----).

How can i make sure that i get events only on the image and not on the rest of area covered by cgrectmake ?

Answer 1

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
  UITouch *touch = [touches anyObject];
  if ([touch view] == yourDesiredImage) {
    // Do something here
  }
}

EDIT: maybe you can try UITapGestureRecognizer instead:

UITapGestureRecognizer * tapGestureRecognizer = [[UITapGestureRecognizer alloc] init];
[tapGestureRecognizer addTarget:self action:@selector(yourTouchMethod:)];
[tapGestureRecognizer setNumberOfTapsRequired:1];
[shutter addGestureRecognizer:tapGestureRecognizer];
[tapGestureRecognizer release];