A developer answers unanswered questions from a Swift Group Lab session, covering Swift 6 migration, actor isolation defaults, @preconcurrency imports, the NonisolatedNonsendingByDefault setting, Sendable conformance with subclassing, and how to handle synchronous work in async contexts. Topics include when to use MainActor vs nonisolated defaults, what @preconcurrency actually means for safety, the ~Sendable mechanism for subclassable types, and recommendations on Approachable Concurrency settings for iOS apps.
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