The take-home app you submitted has a singleton ImageCache created with static let shared (with var storage: [URL: UIImage] inside) that several screens read and write from background queues. The interviewer asks: "What happens if you build this project in Swift 6 language mode?"
Swift 6 strict concurrency rejects a static let shared of a non-Sendable type with a 'not concurrency-safe' compile error. A class holding a mutable dictionary isn't Sendable, so the build breaks, and a latent data race surfaces at compile time.
ConcurrencyMultiple choiceAdvanced
Under Swift 6 strict concurrency, which of the following are treated as Sendable (or…
#strict-concurrency #sendable #actor
TestingShort answerExpert
How do you reproduce or detect a data race in concurrent code that uses actors and Tasks?
#sendable #actor
ConcurrencyShort answerBasics
This code gets called from several threads, and count comes out lower than expected. Can…
#actor
ConcurrencyShort answerExpert
This image cache actor built with Swift Concurrency sometimes sends two network requests…
#actor