Wrong UITapGestureRecognizer being called (in the wrong UIView)

Question

I've got a ViewController which contains a vertical UIScrollView. To said UIScrollView I add multiple subviews, each of which contains a horizontal UIScrollView which contains some images and is paged.

When creating these subviews, I add a UITapGestureRecognizer to their UIScrollViews to detect single taps on them and perform an action depending on which image was being displayed.

The problem I've got is that if I have 2 such subviews and tap the first one in line, it picks up the wrong subview and tries to fire the method on the second one. So, say I tapped the 3rd image of the 1st subview, and the 2nd subview only has 1 page, then the app crashes.

Here's the constructor for my subview:

- (id)init {

    NSArray *arrayOfViews = [[NSBundle mainBundle] loadNibNamed:@"GalleryLeafView"
                                                      owner:nil
                                                    options:nil];
    GalleryLeafView *galleryLeafView = [arrayOfViews objectAtIndex:0];
    self = galleryLeafView;

    if (self) {

        // Set up tap gesture recognizers on the ScrollView
        UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(imageTapped)];
        tapGestureRecognizer.numberOfTapsRequired = 1;
        [self.scrollView addGestureRecognizer:tapGestureRecognizer];
    }

    return self;
}

Here's the selector method, just in case:

- (void)imageTapped {

    NSString *filename = [imageFilenames objectAtIndex:[self getCurrentPage]];
    NSString *caption = [captions objectAtIndex:[self getCurrentPage]];

    [self.galleryLeafViewDelegate galleryLeafViewPressedWithFilename:filename caption:caption];
}

Any ideas as to why this happens? Or how I can work around this?

JakeP JakeP · Accepted Answer · 2014-11-21T10:35:14

Ok, this was a yet another of my rookie mistakes ;/

In the selector method you can see I'm doing stuff on imageFilenames and captions arrays. They should've been strong properties, not just variables set in the .m file. Everything works fine now.

Wrong UITapGestureRecognizer being called (in the wrong UIView)

1 Answers