tap gesture not recognized on uiimageview

Question

I added two uiimageviews, one on another subview uiview (imageview1,imageview2). In the first view the top uiimageview is

Answer 1

UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(oneTap:)];
singleTap.numberOfTapsRequired = 1;
singleTap.numberOfTouchesRequired = 1;
singleTap.delegate = self;
[imageview1 addGestureRecogniser:singleTap];
[singleTap1 release];

imageview1.userInteractionEnabled = YES; //disabled by default