In a CollectionView, some cells should have an additional subview or layer. The CollectionView can be told to resize it's cells, thus all content needs to resize appropriately.
Currently, the cell is initialized from a nib containing a cell with imageview; the cell nib is linked to a custom UICollectionViewCell subclass, that only does the init. Autoresize subviews is checked.
The CollectionView is told to resize the cell by a value derived and returned in sizeForItemAtIndexPath:. I have subclassed a FlowLayout but it only specifies ScrollDirection and Insets.
All of that is working fine. Problem: How do I add subview/layer to the cell so it also resizes correctly? I tried adding subviews and layers with translatesAutoresizingMaskIntoConstraints off, but these do not automatically change size at all. Also tried to use code frame/view instead of nib.
The best I got now is a cell.contentView.layer sublayer which I add in cellForItemAtIndexPath:; that is "manually" resized by storing the cell's frame.size from sizeForItemAtIndexPath:, which is not only ugly but also ends up with the sublayer having various sizes for different cells.
Any help appreciated!
The solution was to turn off AutoConstraints for the cell xib and activate the flexible width/height arrows in the AutoResize for the imageviews.