How To Detect "Touch Down" in superview of UIScrollView?

Question

I have a UIView that contains a UIScrollView and I want to be able to capture the "Touch Down" event in the UIView any time the user taps on the UIScrollView.

I've tried including all the touchesBegan/Ended/Cancelled handlers in my UIViewController but none of them get fired when tapping inside the UIScrollView contained in the main UIView.

What is the best way to accomplish this?

score 2 · Accepted Answer · answered Apr 08 '10 at 03:00

2

In the UIView, implement touchesBegan:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    // assign a UITouch object to the current touch
    UITouch *touch = [[event allTouches] anyObject];

    // if the view in which the touch is found is myScrollView
    // (assuming myScrollView is the UIScrollView and is a subview of the UIView)
    if ([touch view] == myScrollView) {
        // do stuff here
    }
}

A side note: make sure userInteractionEnabled is set to YES in the UIView.

answered Apr 08 '10 at 03:00

Arseniy Banayev

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And, per my self-answer below, make user userInteractionEnabled=NO for the scrollview – wgpubs Apr 12 '10 at 18:09
3

This defeats the purpose of uiscrollview as we have to implement the scrolling operation under the "do stuff here". – Gamma-Point Dec 20 '11 at 09:14

score 1 · Answer 2 · answered Apr 08 '10 at 07:52

You can also implement hitTest:withEvent: in your UIView subclass. This method gets called to determine which subview should receive touch event. So here you can either just track all events passing through your view not or hide some of the events from subviews. In this case you may not need to disable user interaction for your scrollview.

See more details on this method in UIView class reference.

score 1 · Answer 3 · edited Feb 23 '12 at 11:40

1

You can also add a gesture recognizer to your superview. For example a tap gesture if you need to activate/deactivate things like buttons overlaying the scroll view :

self.tap = [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onTap:)] autorelease];
tap.numberOfTapsRequired = 1;

["containerView" addGestureRecognizer:tap];

Gestures do preserve the scroll view interaction

edited Feb 23 '12 at 11:40

Stephen

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answered Feb 23 '12 at 10:26

Menator

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tapgesturerecognizer detects only TAPS (touchDown+touchUp). So it is now what we want for touchDown events detection. – kas-kad Aug 01 '13 at 13:05

score -3 · Answer 4 · answered Apr 08 '10 at 07:31

-3

You need to disable user interaction with the scroll view as such ...

scrollView.userInteractionEnabled = NO;

Once disabled, the UIScrollView's superview gets the touchesBegan event.

answered Apr 08 '10 at 07:31

wgpubs

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1

This defeats the purpose of having a scroll view in the first place. – Zorayr Mar 03 '14 at 00:03

How To Detect "Touch Down" in superview of UIScrollView?

4 Answers4