An interesting problem I met during work, the previous developer placed a child UIButton outside of its parent UIView bounds, hence the tap on the UIButton is not registered. I troubleshooted 15 minutes for this problem and found the correct keyword to google for in Stack Overflow.

Writing this down in case my future self needs to reference it.

//override this in a UIView Custom Class

// check if any sub element inside view is outside bounds of the view
// if yes, expand the hitable area of view with its sub element
// http://stackoverflow.com/questions/11770743/capturing-touches-on-a-subview-outside-the-frame-of-its-superview-using-hittest
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
	if (!self.clipsToBounds && !self.hidden && self.alpha > 0) {
		for (UIView *subview in self.subviews.reverseObjectEnumerator) {
			CGPoint subPoint = [subview convertPoint:point fromView:self];
			UIView *result = [subview hitTest:subPoint withEvent:event];
			if (result != nil) {
				return result;
			}
		}
	}
	
	return nil;
}

Source : http://stackoverflow.com/questions/11770743/capturing-touches-on-a-subview-outside-the-frame-of-its-superview-using-hittest