Open Radar

 
Summary:
Populating a UICollectionView with cells which have width and height calculated via AutoLayout can cause an infinite loop crash in UICollectionView _updateVisibleCellsNow:

Steps to Reproduce:
1. Create a UICollectionView with a single cell prototype
2. Constrain the cell prototype to be sized with AutoLayout based on some variable attribute (for instance a multiline UILabel)
3. Set a reasonable estimatedItemSize on the UICollectionViewFlowLayout
4. Provide input data which will cause some of the cells to wrap lines and become taller than others, and contains more items than fit on a single screen
5. Run on an iPhone simulator or device, scroll the collection view

Expected Results:
The collection view correctly sizes all of its cells based on their constraints

Actual Results:
The app crashes in an infinite loop inside _updateVisibleCellsNow:

Notes:
See attached project for a quick example with extremely minimal code. Example text from a prototype social media app. Simply build and run in an iPhone simulator and scroll down.