Crash with two fingers & centroid issue

[lukescott]

If you hold your finger on one cell, then place a finger on the other the center of the two fingers is used (different issue). When you lift the first finger it crashes with:

*\ Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'request for number of items before section 2147483647 when there are only 5 sections in the collection view'

I suspect it might have something to do with a numberOfItemsInSection call somewhere, but I'm going to have to do some more debugging to find out.

[martijnpolak]

Hi, I'm running into this issue and it looks like you can simply avoid it by setting maximumNumberOfTouches on _panPressGestureRecognizer to 1 in LSCollectionViewHelper::initWithCollectionView. You just have to define the property as a UIPanGestureRecognizer (instead of a UIGestureRecognizer) in the header file. Looking at the odd behaviour we get when using multi touch this might be the simplest solution, unless there's a benefit to having multi touch enabled?

[gouravgupta72]

Hi, I'm using this on xcode-5, but not able to set maximumNumberOfTouches on _panPressGestureRecognizer to 1in LSCollectionViewHelper. I set multiple touch to no on my cell and collection view but still it causes crash.

Is there any other way to avoid this crash...? Thanks in advance.

[chewedon]

gouravgupta72,

I found out the problem why you can't set maximumNumberOfTouches.

In LSCollectionViewHelper's initWithCollectionView, you have this:

_panPressGestureRecognizer = [[UIPanGestureRecognizer alloc]
                                  initWithTarget:self action:@selector(handlePanGesture:)];
_panPressGestureRecognizer.delegate = self;

However, if you check the LSCollectionViewHelper.h file, you'll see panPressGestureRecognizer is declared as:

@property (nonatomic, readonly) UIGestureRecognizer *panPressGestureRecognizer;

I simply changed this to:

@property (nonatomic, readonly) UIPanGestureRecognizer *panPressGestureRecognizer;

Then I'm able to set:

_panPressGestureRecognizer.maximumNumberOfTouches = 1;

Not sure what effect this has on the draggable collection view library but it seems to fix the two finger crash for me too.

[angelvasa]

Just add below code snippet in LSCollectioViewHelper and you are done.

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
    if (gestureRecognizer.numberOfTouches < 1) {
        return YES;
    } else {
        return NO;
    }
}