1601 - Crash on createTileArrays() - Not Thread Safe

[danbenner-vega]

• For some reason the tileOverlays was set as an array. It's never used as an array. The parent never sees more than one in the array. I made it a single object. Seems to have solved the problem.
• Second, I've wrapped problematic calls to refresh() function to stay on main thread now.

[brentvegafederal]

One small note to think about, but code looks good.

[paulsolt-ofsw]

This solution is not the right solution.

We have a concurrency bug that I documented with multiple threads accessing the same shared data in the createTileOverlays() method. Changing the type of the published property might punt the crash and doesn't solve anything about concurrent access. It might appear to be less likely to crash, but it is still just as unsafe.

Both Task 10 and Task 11 are modifying the same shared resource from concurrent queues. This is unsafe code to be modified by both Tasks concurrently.

We need to protect with either actor, serial queue, or static @mainactor protections to prevent modifying shared state from two different threads at the same time.

[paulsolt-ofsw]

Looks better. I'm not sure what approach actually solves the concurrency issue.

It almost feels like it's because the Task might be on a background thread inside the .sink. So that we'd need await MainActor.run { to do the main thread work on the proper thread.

[paulsolt-ofsw]

Looks good. I have not seen a crash on the simulator or iPhone 15 Pro Max running on this branch.

The new changes should make this logic safer. In the future we can explore more @mainactor changes, or make it the default in Swift 6.2 with Xcode 26.