Specifying one Dimension of Cells in UICollectionView using Auto Layout

Question

In iOS 8 the UICollectionViewFlowLayout supports automatically resizing cells based on their own content size. This resizes the cells in both width and height a

Answer 1

Try fixing your width in the preferred layout attributes:

- (UICollectionViewLayoutAttributes *)preferredLayoutAttributesFittingAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes {
    UICollectionViewLayoutAttributes *attributes = [[super preferredLayoutAttributesFittingAttributes:layoutAttributes] copy];
    CGSize newSize = [self systemLayoutSizeFittingSize:CGSizeMake(FIXED_WIDTH,layoutAttributes.size) withHorizontalFittingPriority:UILayoutPriorityRequired verticalFittingPriority:UILayoutPriorityFittingSizeLevel];
    CGRect newFrame = attr.frame;
    newFrame.size.height = size.height;
    attr.frame = newFrame;
    return attr;
}

Naturally you also want to ensure that you setup your layout correctly to:

UICollectionViewFlowLayout *flowLayout = (UICollectionViewFlowLayout *) self.collectionView.collectionViewLayout;
flowLayout.estimatedItemSize = CGSizeMake(FIXED_WIDTH, estimatedHeight)];

Heres something I put on Github that uses constant width cells and supports dynamic type so the height of the cells updates as the system font size changes.