Swift Interview Prep - Programming

Copy on write is an optimization where value types sharing the same underlying storage delay copying until one is mutated. Standard collections like Array use it, so passing them around is cheap, and an actual copy of the buffer happens only when you modify a shared instance.

A struct is a value type copied on assignment with no inheritance, while a class is a reference type shared by reference and supporting inheritance and deinitializers. Structs give predictable independent copies; classes give shared identity, which you choose when instances must be shared.

A retain cycle occurs when two objects hold strong references to each other, or a closure captures self strongly while the object retains the closure. You fix it with a capture list using weak or unowned, or by making one reference weak so the cycle can be broken.

Use one when a value is nil briefly during initialization but is guaranteed to be set before use, such as an outlet connected from a storyboard. It behaves like a non-optional after setup, but accessing it while nil crashes, so use it sparingly and deliberately.

Effective Swift interview preparation covers optionals, value versus reference types, closures, protocols, generics, and memory management with automatic reference counting. Review common data structures and algorithms in Swift, and practice explaining how ARC prevents leaks. Writing small Swift programs to test each concept, then reasoning aloud about them, prepares you for both technical and whiteboard questions.

During Swift interview preparation for iOS roles, expect questions on the view lifecycle, memory management and retain cycles, delegation and closures, and concurrency with Grand Central Dispatch or async await. Interviewers also ask about UIKit versus SwiftUI and app architecture patterns. Building real features and understanding why each pattern exists helps you answer with confidence.

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Our questions are written for structured educational practice and can give a useful snapshot of your current knowledge in the tested topics.