UserDefaults: a wolf in sheep's clothing

on YouTube ↗34m

" summary

UserDefaults can silently return nil while the device is locked or during pre-warmed launches, allowing that temporary nil to overwrite real data; a reliable repro is live activity + reboot + open, which fails every time. Investigation uses file protection, checking isProtectedDataAvailable, switching to file-backed storage in an app group with atomic writes and a dispatch queue, coordinating cross-process access with NSFileCoordinator, caching in memory and observing disk changes. A Swift Codable + property‑wrapper library is built and published and it works to avoid the data-loss class.

AI-written summary · about

" chapters (10)

1. 0:00Introduction
2. 3:09UserDefaults data loss bug
3. 8:01UserDefaults fails on locked devices
4. 11:34Pre-warming risks
5. 13:41Impact of UserDefaults data loss
6. 15:44Workarounds for locked devices
7. 17:30Safer alternative to UserDefaults
8. 24:11Modern Swift storage design
9. 30:12SwiftUI with custom storage
10. 32:40Key takeaways

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