iOS 26 Beta: UICollectionView estimatedDimension causes layout feedback loop (worked in iOS 18)

Issue Description

We're experiencing a new recursive layout crash in UICollectionViewCompositionalLayout on iOS 26 Beta when using estimatedDimension. The same code works perfectly on iOS 18.

Environment

  • iOS 18.x: ✅ Works fine
  • iOS 26 Beta: ❌ Crashes with layout feedback loop

Crash Details

Question

Is this an intentional change in iOS 26? Are there new best practices for using estimatedDimension in compositional layouts?

Temporary Workaround

Using absoluteDimension instead of estimatedDimension resolves the crash, but we lose dynamic sizing capabilities.

iOS 26 Beta: UICollectionView estimatedDimension causes layout feedback loop (worked in iOS 18)
 
 
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