iOS memory management interview questions

Memory management is a reliable iOS interview topic because it reveals whether you understand what the runtime is doing beneath your code.

What gets asked

Expect questions on Automatic Reference Counting, the difference between strong, weak, and unowned references, and how retain cycles form and break. A common exercise is spotting a cycle in a closure or delegate relationship and fixing it with a capture list. Follow-ups probe when to choose weak versus unowned and why delegates are usually weak.

Answering with confidence

Explain the mechanism, not just the rule. ARC releases an object when its strong reference count reaches zero; a cycle keeps that count above zero forever, so the memory is never reclaimed. Mention confirming a leak with the Xcode memory graph debugger or Instruments rather than guessing. That precision reads as senior.

Go deeper than a summary

Share Your Screen works topics like this through in full: 75 solved Swift problems with tests, 9 real case studies, and 7 annotated mock interviews, so you rehearse the live round instead of just reading about it.

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Frequently asked

What is the difference between weak and unowned?

Use weak when the reference may become nil during its lifetime; use unowned when the referenced object is guaranteed to outlive the reference, avoiding the optional.

How do you find a retain cycle?

Reproduce the leak, then use the Xcode memory graph debugger or Instruments Leaks to see which objects are retaining each other.