I run in the same problem. Code runs under 6.1 and crashes under 7.0 I solved the issue the following way: In the function -(NSInteger) numberOfSectionsInCollectionView:(UICollectionView *)collectionView I call [myCollectionView.collectionViewLayout invalidateLayout]; That´s all.
select collectionview in storyboard go to size inspector change estimate size to none
This worked for me: [self.collectionView reloadData]; [self.collectionView performBatchUpdates:^{} completion:^(BOOL finished) { /// collection-view finished reload }]; Swift 4 syntax: collectionView.reloadData() collectionView.performBatchUpdates(nil, completion: { (result) in // ready })