Concurrency
Actor reentrancy
This image cache actor built with Swift Concurrency sometimes sends two network requests for the same key. The actor protects its state, so why does this happen?
actor ImageCache {
private var cache: [URL: UIImage] = [:]
func image(for url: URL) async throws -> UIImage {
if let hit = cache[url] { return hit }
let img = try await download(url)
cache[url] = img
return img
}
}How would an interviewer hear this answer? You'll see whether they'd move on, dig in, or say no, and which sentences would trip you up. Your score doesn't change.