Using UILongPressGestureRecognizer For Subviews of UIScrollview

Question

For the past four hours, I have tried many Stack Overlow solutions but none have helped solve my problem.

Here it is,

• I have a UIScrollView

Answer 1

Since your UIScrollView is the common parent, that's probably where your gesture recognizer needs to be. You can determine which subview is being pressed by looking at the location of the point supplied in your action. So, the individual subviews do not need gesture recognizers.

So, you would do something like this:

- (void)longPressDidFire:(UILongPressGestureRecognizer *)sender
{
    if (sender.state == UIGestureRecognizerStateEnded)
        CGPoint point = [sender locationInView:scroll];
        UIView *tappedView = [scroll hitTest:point withEvent:nil];

So, then you have the view that was long-pressed.

Other things that could cause the action not to fire would be a delegate problem or if the scroll is contained by another view that is intercepting the touch.

HTH

Answer 2

Woohoo it works!

The problem was:

imgContainer was a UIView with an empty frame with several UIImageViews as subviews

I was under the impression that as I added a subview to imgContainer, imgContainer would expand.

This is not true.

I had to set imgContainer's frame to the same content frame as the scroll view and then everything became ok.

I hope this answer helps any other future iOS firs timers like me.

Answer 3

I know this is a bit late and an answer has been chosen, but in case someone else wants a nice simple solution if you've got iOS7.

Inside your delegate of the UILongPressGestureRecognizer implement the gestureRecognizer:shouldRequireFailureOfGestureRecognizer:otherGestureRecognizer selector

Check if otherGestureRecognizer is a UIPanGestureRecognizer and return YES, otherwise return NO

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    if ([otherGestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
        return YES;
    }

    return NO;
}

The scroll view will actually produce a UIScrollViewPanGestureRecognizer, which is part of the private API, but it's a subclass of UIPanGestureRecognizer so the above works fine.

To support iOS6 or below, then you'll need to loop through the gestureRecognizers of the UIScrollView, detect which one is a UIPanGestureRecognizer and perform the requireGestureRecognizerToFail selector on your UILongPressGestureRecogizer with that.

Answer 4

Instead of

 [scroll addGestureRecognizer:longPress]; 

Add the gesture on your subviews, right after you declare them and before you add them to scrollview

 [subview addGestureRecognizer:longPress]; 

Answer 5

your code seems to be fine,it should work i think.i used below code and its working fine for me.

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
longPress.delegate = (id)self;
longPress.minimumPressDuration=0.05;
imageView.userInteractionEnabled = YES;
[imageView addGestureRecognizer:longPress];

and its method,

- (IBAction)handleLongPress:(UILongPressGestureRecognizer *)sender {
   NSLog(@"detected");

if (sender.state == UIGestureRecognizerStateEnded){
     UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Alert" message:@"YES"    delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
     [alert show];
   } 
}

Here i took imageView as subview of scrollview as u said