iOS 6.0: UICollectionView doesn't respect clipsToBounds with pagingEnabled

Question

Background

I am implementing a UICollectionView (for the first time) in an effort to achieve a paged horizontal scroll view of tiles. I\'d

Answer 1

Many thanks for the tip about using a negative minimumLineSpacing. I created a tester application which uses a collection view cell loaded from a xib file. The cell has a transparent background and an “inner” view for the cell's content.

In this way, a custom flow layout is not necessary.

https://github.com/j4johnfox/CollectionViewTester

Answer 2

I'm not an expert in collectionView, but it could be possibly do with this line in cellForItemAtIndexPath:

[cell.contentView addSubview:label];

Everytime it's called, another label subview is added to cell. Either check for an existing label or subclass UICollectionViewCell?

Answer 3

You'll want to also override -pointInside:withEvent: to allow scroll gestures to start outside the frame of the collection view. I do this using a UIEdgeInsets property in my collection view subclass:

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
    CGRect extendedBounds = UIEdgeInsetsInsetRect(self.bounds, self.touchAreaInsets);

    return CGRectContainsPoint(extendedBounds, point);
}

If you don't need App Store safety, you can override _visibleBounds to avoid negative spacing hacks:

- (CGRect)_visibleBounds {
     return UIEdgeInsetsInsetRect(self.bounds, self.touchAreaInsets);
}

If you're not too pressed on code size and need App Store safety you could also subclass PSTCollectionView and possibly override visibleBoundRects for the same effect.

Answer 4

Turns out the solution to this was actually quite simple. I just needed to overlap the UICollectionViewCell cells by enough pixels to have them still show within the collectionView's frame after the paged scrolling finishes. The relevent code was

layout.itemSize = CGSizeMake(300, 300);
layout.minimumLineSpacing = -20.0;

And I subclassed the UICollectionViewFlowLayout and overrode the (CGSize)collectionViewContentSize method to return the non-overlapped size of the cells.