Unit Tests crash with estimatedItemSize on Collection View Flow Layout - EXC_ARITHMETIC

Question

I have a UICollectionViewFlowLayout with an estimatedItemSize set.

When I run my application, everything works fine, but in my unit tests, I get an EXC_ARITHMETIC crash every time I hit collectionView:dequeueReusableCellWithReuseIdentifier:.

I know this is due to my estimatedItemSize as removing it fixes the crash.

Does anyone have any idea why this is happening?

Thanks

Answer 1

I have the same problem with UICollectionViewFlowLayout and estimatedItemSize. I filed a radar and Apple closed it as a duplicate with no further suggestions as a workaround. My best guess and research thus far indicates that self-sizing cells are fundamentally broken on iOS 8 / 9.

Try random values of estimatedItemSize. For me, setting sizes that closely match the resulting size of your cells cause a crash but sizes much smaller than your cells (1,1) for example do not crash.

I know this is not what you want to hear but it might be the only option until Apple fixes UICollectionView.