tap gesture not recognized on uiimageview

Try setting setUserInteractionEnabled:YES before adding gesture recognizer.

[imageview1 setUserInteractionEnabled:YES]
[imageview2 setUserInteractionEnabled:YES]

[imageview1 addGestureRecognizer:singleTap];
[imageview2 addGestureRecognizer:singleTap1];   

Update:

After the comment you have made I suggest you bring your views to the top before detecting the tap event. Because parent imageView is above and catches these taps.

[yourparentview bringSubviewToFront:imageview1];
[yourparentview bringSubviewToFront:imageview2];