UITableView with insetGrouped style

[nizarjak]

Noticed an issue while snapshotting UITableView with insetGrouped style. It layouts correctly during run but on snapshots it has artifacts between first & second and second last & last rows in a section.

Does anyone have any idea what happened? Tried delaying layout before taking snapshot, but that was not the case. Snapshot are consistent throughout multiple runs.

I've created a simple project with as little code as possible to replicate the issue. Snapshot taken from simulator iPhone 11 (13.4.1) using Xcode 11.4.1.

GroupedTableViewVC.zip

[piercifani]

Yep, happening here as well... 😢

[jaetzold]

Same happens when using https://github.com/uber/ios-snapshot-test-case btw.

[jaetzold]

Probably related to #358

[lukeredpath]

I had this problem on my current project - the workaround was to set drawHierarchyInKeyWindow: true which causes the library to render the view using drawHierarchy(in:afterScreenUpdates:) instead.

Worth noting that this workaround may introduce other problems - whilst drawInContext uses the CPU, drawHierarchy(in:afterScreenUpdates:) uses the GPU and may result in inconsistent results on different machines, particularly CI as I'm currently struggling with (see #419).

[stephencelis]

I'm going to convert this to a discussion since it seems to be a more general bug that affects other frameworks, and @lukeredpath has a workaround. If someone figures out how to apply this fix directly in a strategy, we'd definitely take a fix, but for now going to surface discussion over on the forums so that issues can focus on bugs in the library.