Concentric corner radius for grouped cells in UICollectionView on iOS 26

What is the recommended way to obtain the concentric corner radius for views within grouped UICollectionView cells?

In the most basic example, a UICollectionView with one section and one cell, we observe the cell takes almost the shape of a capsule, but it is indeed not a capsule.

What is the way to obtain the radius of the grouped area from within the cell or its registration? I would like to layer elements on top that are concentric to the cell's clip shape.

I've tried using custom views with .concentric UICornerConfigurations, setting .cornerConfiguration on the cell and on a custom backgroundView and I've even tried obtaining the .effectiveRadius of the cell after layout (returns 0.0). As of Xcode 26.0 Beta 7, nothing works.

This seems like a huge omission; what am I missing here?

It appears that the only way to access any information about a cell's corner radius is obtained only via the cell's layer cornerRadius. List cells never get their corner configuration updated in grouped configurations.

Further, I have noted that as of Xcode 16.0 Beta 7, accessing .cornerConfiguration on UICollectionView.appearance() causes a segfault (FB20029166).

Concentric corner radius for grouped cells in UICollectionView on iOS 26
 
 
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