UIKit & SwiftUI internals interview questions
Scenario-style prompts with sample answer outlines. Focus is on how you would design and reason in real codebases.
- 01View bounds and layout timingWhere do common mistakes happen when reading view bounds or forcing layout too early?
- 02Bounds, frame, and the iOS coordinate systemExplain how bounds and frame differ, what coordinate system each uses, and how center fits in. Why does this matter when positioning subviews or applying transforms?
- 03Responder chain and hit testingHow does hit testing decide which view receives a touch?
- 04How Auto Layout worksAt a high level, how does Auto Layout work? What are the major gotchas?
- 05Table and collection views: reuse, prefetching, and diffingWhy do images or text 'flash' wrong in cells during fast scrolling?
- 06SwiftUI state: @State, @StateObject, and @ObservedObjectWhen would you use @State vs @ObservedObject vs @StateObject?
- 07SwiftUI lists, identity, and expensive body workScrolling stutters in a SwiftUI List with many rows. What causes unnecessary view invalidation, and how do you structure rows for performance?
- 08UIKit and SwiftUI interopHow do you embed SwiftUI in UIKit or wrap UIKit for SwiftUI, and what usually goes wrong at the boundary?
- 09Modals: ownership, boundaries, and passing data backYou need to show a second screen on top of the current one and hand information back when it finishes (or cancel without changing anything). How do you decide where state lives, how the two screens should talk to each other, and what usually goes wrong if that contract is vague?
- 10Timer vs CADisplayLinkWhat's the difference between Timer and CADisplayLink? When would you pick one over the other for UI-related work?
