What does @escaping mean on a closure parameter and when do you actually need it?
Explain why Swift split escaping and non-escaping closures — lifetime, performance, and retain-cycle safety — then cover @autoclosure, trailing syntax, and @Sendable
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Questions tagged “Memory Management”
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How does Swift's Dictionary work under the hood?
Walk through Swift Dictionary as a CoW hash table — hashing invariants, collisions, complexity traps, nil removal, ordering, concurrency, and key design for senior interviews
What is the difference between NSCache and Dictionary?
Compare Dictionary and NSCache on one concrete example, an image cache for a photo feed, and show where the two diverge on thread safety, automatic eviction, and key and value rules
How would you demonstrate Copy-on-Write behavior with a custom struct?
Demonstrate Copy-on-Write with a value-typed linked list that shares storage on assignment and copies it only when a mutation occurs using isKnownUniquelyReferenced.
What's the difference between strong, weak, and unowned references?
Under ARC, strong keeps an object alive, unowned tracks a direct non-owning pointer that must outlive use, and weak goes through a side table so access can become nil after deinit
What is a retain cycle and how do you avoid it?
Define retain cycles in ARC terms, show the most common ways teams create them, and explain how to prevent and debug them in production code
How does struct memory layout work in Swift?
Explain MemoryLayout, padding, alignment, and stride; show why stored-property order changes a struct's footprint; and connect it to arrays, performance, and low-level interop