iOS Architecture interview questions

SwiftUI, modularization, and memory management.

3 questions in Mobile Engineering.

Mobile EngineeringA 15-minute read on how the topic fits together, before the questions.Mobile engineering fundamentals59 short answers on one page, for revising rather than studying.

medium2

mediumConceptScenario

How do retain cycles happen in Swift closures and delegates, and how would you find one in an app that is slowly leaking memory?

A closure or delegate reference that captures its owner strongly, while the owner also holds that closure or delegate strongly, forms a cycle ARC cannot break on its own, and the fix is weak or unowned capture chosen by lifetime, not by habit. Use this IOS answer to show the decision, trade-off, and evidence rather than a memorised definition.

4 minmid, senior

mediumConceptScenario

Your SwiftUI screen redraws constantly and scrolling stutters - how would you find out why, and what state-management mistake usually causes it?

A re-render storm usually comes from one large ObservableObject whose @Published properties fan out too widely, so any single field change invalidates every view reading the object rather than just the row that changed. Use this swiftui answer to show the decision, trade-off, and evidence rather than a memorised definition. It also connects state management to the point an interviewer is testing.

4 minmid, senior

hard1

hardDesignScenario

You're asked to break up a five-year-old iOS app that has become one enormous Xcode target - how would you approach modularising it, and what does it cost you?

Modularising means carving the app into Swift packages along feature and layer boundaries so build graphs and ownership become explicit, at the cost of slower initial builds, careful dependency direction, and real discipline about what each module exposes publicly. Use this IOS answer to show the decision, trade-off, and evidence rather than a memorised definition.

4 minsenior, staff