the behavior of the UICollectionViewFlowLayout is not defined, because the cell width is greater than collectionView width

Question

2015-08-18 16:07:51.523 Example[16070:269647] the behavior of the UICollectionViewFlowLayout is not defined because: 2015-08-18 16:07:51.523
Example

Answer 1

I found that this worked quite well for UICollectionViewController and animated correctly:

- (void)viewWillTransitionToSize:(CGSize)size
       withTransitionCoordinator:(id)coordinator {
    // Ensure the layout is within the allowed size before animating below, or 
    //  `UICollectionViewFlowLayoutBreakForInvalidSizes` breakpoint will trigger
    //  and the logging will occur.

    if ([self.collectionView.collectionViewLayout isKindOfClass:[YourLayoutSubclass class]]) {
        [(YourLayoutSubclass *)self.collectionView.collectionViewLayout updateForWidth:size.width];
    }

    // Then, animate alongside the transition, as you would:

    [coordinator animateAlongsideTransition:^
        (id  _Nonnull context) {
            [self.collectionView.collectionViewLayout invalidateLayout];
        }
                                 completion:nil];

    [super viewWillTransitionToSize:size
          withTransitionCoordinator:coordinator];
}

///////////////

@implementation YourLayoutSubclass

- (void)prepareLayout {
    [super prepareLayout];

    [self updateForWidth:self.collectionView.bounds.size.width];
}

- (void)updateForWidth:(CGFloat)width {
    // Update layout as you wish...
}

@end

... See inline code comments above for explanation.