Detect touch position on UiScrollView

Question

I need to get the touch position from a UIScrollView. But when I create a subclass for my scrollview :

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
  NSArray *touchesArray = [touches allObjects];
  UITouch *touch = (UITouch *)[touchesArray objectAtIndex:0];
  CGPoint point = [touch locationInView:self];
  self.position = point;}

The function touchesBegan isn't always called. If I swipe fast, touchesBegan is never called, but scrollViewDidScroll gets directly called instead.

I can't use UIGesture (UITapGestureRecognizer, ... ) because users don't tap or swipe.

Are there others methods to get the position from UIScrollView ?

EDIT :

Thanks ThXou : https://stackoverflow.com/a/15763450/1752843

UIScrollView subclass :

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
    self.position = point;
    return self;
}

iVenky · Answer 1 · 2013-04-02T11:30:50.230

7

To detect the touch location inside scrollview, try this code

UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(singleTapGestureCaptured:)];
[scrollView addGestureRecognizer:singleTap]; 

- (void)singleTapGestureCaptured:(UITapGestureRecognizer *)gesture
 { 
   CGPoint touchPoint=[gesture locationInView:scrollView];
 }

edited Apr 02 '13 at 11:30

answered Apr 02 '13 at 11:13

iVenky

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But the function "touchesBegan" or "touchesMoved" are never called when my scrollview is scrolled. And I want to get the touch when my scrollview is used. – VivienCormier Apr 02 '13 at 11:21
Even though "touchesBegan" is empty, her are never called. – VivienCormier Apr 02 '13 at 11:27
Sorry try the above code. other method is yu need to call the sub classes . For further details, check out this link http://iosdevelopertips.com/user-interface/detect-single-tap-in-uiscrollview.html – iVenky Apr 02 '13 at 11:32
To detect touchesBegan and touchesMoved, sub-classing is NOT required. You can add the UIScrollViewDelegate to the "h" file and applicable functions to detect touches based on user intention. See http://stackoverflow.com/questions/993280/how-to-detect-when-a-uiscrollview-has-finished-scrolling/20017639#20017639 – bob Nov 21 '13 at 09:22

score 3 · Answer 2 · answered Feb 21 '14 at 12:15

3

You could alternatively use scrollview.panGestureRecognizer's locationInView method to get the coordinates of a touch in your view. This could be in any of scrollView's delegate method depending on your requirements.

answered Feb 21 '14 at 12:15

rounak

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score 2 · Accepted Answer · edited May 23 '17 at 12:06

2

I saw an answer in SO that I think that it can solve you problem. It seems that the SDK doesn't pass the touch handling methods to the UIScrollView subclasses anymore. So, you should to perform a hitTest: to pass the touches to your subclass.

See the answer for more information.

edited May 23 '17 at 12:06

Community

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answered Apr 02 '13 at 11:54

thxou

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Thx! My code : '- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{ self.position = point; return self; }' – VivienCormier Apr 02 '13 at 13:18

Łukasz Gierałtowski · Answer 4 · 2017-09-13T11:12:23.907

1

scrollView.delaysContentTouches = NO;

It will makes that touchesBegan and other touch events will be triggered before scrollViewDidScroll.

The hitTest is a hack and should not be preferred solution.

edited Sep 13 '17 at 11:12

answered Sep 12 '17 at 09:18

Łukasz Gierałtowski

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Detect touch position on UiScrollView

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