Allow UIScrollView and its subviews to both respond to a touch

Question

I want both my UIScrollView and its subviews to receive all touch events inside the subview. Each can respond in its own way.

Alternatively, if tap gestures were fo

Answer 1

A hackish way to achieve your objective - not 100% exact - is to subclass the UIWindow and override the - (void)sendEvent:(UIEvent *)event;

A quick example:

in SecondResponderWindow.h header

//SecondResponderWindow.h

@protocol SecondResponderWindowDelegate
- (void)userTouchBegan:(id)tapPoint onView:(UIView*)aView;
- (void)userTouchMoved:(id)tapPoint onView:(UIView*)aView;
- (void)userTouchEnded:(id)tapPoint onView:(UIView*)aView;
@end

@interface SecondResponderWindow : UIWindow
@property (nonatomic, retain) UIView *viewToObserve;
@property (nonatomic, assign) id  controllerThatObserves;
@end

in SecondResponderWindow.m

//SecondResponderWindow.m

- (void)forwardTouchBegan:(id)touch onView:(UIView*)aView {
    [controllerThatObserves userTouchBegan:touch onView:aView];
}
- (void)forwardTouchMoved:(id)touch onView:(UIView*)aView {
    [controllerThatObserves userTouchMoved:touch onView:aView];
}
- (void)forwardTouchEnded:(id)touch onView:(UIView*)aView {
    [controllerThatObserves userTouchEnded:touch onView:aView];
}

- (void)sendEvent:(UIEvent *)event {
    [super sendEvent:event];

    if (viewToObserve == nil || controllerThatObserves == nil) return;

    NSSet *touches = [event allTouches];
    UITouch *touch = [touches anyObject];
    if ([touch.view isDescendantOfView:viewToObserve] == NO) return;

    CGPoint tapPoint = [touch locationInView:viewToObserve];
    NSValue *pointValue = [NSValue valueWithCGPoint:tapPoint];

    if (touch.phase == UITouchPhaseBegan)
        [self forwardTouchBegan:pointValue onView:touch.view];
    else if (touch.phase == UITouchPhaseMoved)
        [self forwardTouchMoved:pointValue onView:touch.view];
    else if (touch.phase == UITouchPhaseEnded)
        [self forwardTouchEnded:pointValue onView:touch.view];
    else if (touch.phase == UITouchPhaseCancelled)
        [self forwardTouchEnded:pointValue onView:touch.view];
}

It's not 100% conforms to what your were expecting - because your second responder view does not handle the touch event natively via -touchDidBegin: or so, and has to implement the SecondResponderWindowDelegate. However this hack does allow you to handle touch events on additional responders.

This method is inspired by and extended from MITHIN KUMAR's TapDetectingWindow