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🧩 What does it print? Interview puzzles: iOS interview questions

1. What prints to the console? Senior PRO
2. What's guaranteed in the output order? (serial vs concurrent) Middle PRO
3. Will deinit be called? Middle PRO
4. What does this array-of-classes code print? Copy-on-Write Middle PRO
5. Dispatch: what does the protocol extension print? Senior PRO
6. What does this GCD code print? (main.sync and the run loop) Senior PRO
7. What does dropFirst()[0] print? Middle PRO
8. Which recursive types compile? Middle PRO
9. Nested closures: will deinit run? Senior PRO
10. weak var person = Person(): what gets printed? Middle PRO
11. GCD puzzle: output order and where is the deadlock? Senior PRO
12. Capture list: how does { x } differ from { [x] in }? Middle PRO
13. global().async + main.async: what order does it print? Middle PRO
14. defer and return: what does the function return? Junior PRO
15. class func vs static func: does the override compile? Junior PRO
16. willSet / didSet in init and defer: what gets printed? Middle PRO
17. lazy.filter.map.prefix: how many times is map called? Middle PRO
18. sync and async on another queue: what does isMainThread show? Junior PRO
19. An escaping closure inside a mutating struct method Senior PRO
20. Which of these types can be declared weak? Junior PRO
21. asyncAfter with self in a ViewController: when is the screen freed? Middle PRO
22. Copy-on-write: what is a1.count after append? Middle PRO
23. lazy var with a closure: is [weak self] needed here? Middle PRO
24. Dispatch: a method in the type body vs in an extension Middle PRO