I'm using Xcode 6 Beta 3, iOS 8 SDK. Build Target iOS 7.0 using Swift. Please refer to my problem step by step with screenshots below.

I have a UICollectionView in Storyboard. 1 Prototype UICollectionViewCell which contains 1 label in the centre (no autoresizing rule). Purple background was to mark a contentView that is generated in runtime by the Cell I guess. That view will be resized properly base on my UICollectionViewLayoutDelegate eventually, but not on iOS 7. Notice that I'm using Xcode 6 and the problem only happens on iOS 7.

When I build the app on iOS 8. Everything is okay.

Note: Purple is the contentView, Blue is my UIButton with rounded corner.

However, on iOS 7, all the subViews inside the Cell suddenly shrink to the frame of (0,0,50,50) and never conforms to my Autoresizing rule anymore.

I assume this is a bug in iOS 8 SDK or Swift or maybe Xcode?

Update 1: This problem still exists in the official Xcode 6.0.1 ! The best work around is like what KoCMoHaBTa suggested below by setting the frame in cellForItem of the cell (You have to subclass your cell though). It turned out that this is a incompatibility between iOS 8 SDK and iOS 7 (check ecotax's answer below quoted from Apple).

Update 2: Paste this code at the beginning of your cellForItem and things should be okay: