ScrollView gesture recognizer eating all touch events

This should solve your problem.
Detect touch event on UIScrollView AND on UIView's components [which is placed inside UIScrollView]
The idea is to tell the gesture recognizer to not swallow up the touch events. To do this you need to set singleTap's cancelsTouchesInView property to NO, which is YES by default.

UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)];
singleTap.cancelsTouchesInView = NO;
[scrollView addGestureRecognizer:singleTap]; 

Swift 3.0

 let singleTap = UITapGestureRecognizer(target: self, action: #selector(handleTap(_:)))
 singleTap.cancelsTouchesInView = false
 singleTap.numberOfTapsRequired = 1
 scrollView.addGestureRecognizer(singleTap)

And the selector method be like.

@objc func handleTap(_ recognizer: UITapGestureRecognizer) {
  // Perform operation
}

I think the reason is that User Interaction Enabled is set to false for UIImageView. You should set it to true to enable tapping in it