Swift with Mayur: iOS interview questions, answered
901 iOS interview questions across 29 topics, with clear answers, common traps, likely follow-ups, animated explainers, hands-on labs and quizzes.
Topics
- Swift language: Types, optionals, protocols, generics, closures, properties, errors, strings, dispatch.
- Foundation & stdlib: Collections, COW, dates, URLs, Codable options, caches and locks.
- Memory, ARC & runtime: Retain cycles, weak/unowned, side tables, copy-on-write, leaks.
- Objective-C & interop: Message send, selectors, categories, nullability, swizzling.
- Compiler & language internals: SIL, specialization, existentials, inlining, library evolution.
- iOS platform internals: Sandbox, lifecycle, run loop, launch, jetsam, background modes.
- UIKit: Responder chain, view controllers, collection views, transitions.
- SwiftUI: Identity, state, the render loop, layout, navigation, Observation.
- Layout, rendering & animation: Auto Layout, CALayer, compositing, Core Animation, text.
- Concurrency: GCD, OperationQueue, tasks, actors, Sendable, Swift 6 isolation.
- Combine: Publishers, operators, subjects, schedulers, backpressure.
- Networking: URLSession, HTTP/3, caching, auth refresh races, retries.
- Persistence & data: Files, Keychain, SQLite, Core Data, SwiftData, migrations.
- Security & privacy: ATS, Keychain, CryptoKit, privacy manifests, ATT, pinning.
- Architecture & API design: MVVM, TCA, unidirectional flow, DI, module boundaries.
- Modularization & SPM: Targets, link types, xcframeworks, build settings, CI graphs.
- System frameworks: Notifications, Location, MapKit, HealthKit, StoreKit, Wallet.
- Media & graphics: AVFoundation, capture, audio sessions, ImageIO, Metal.
- Extensions, widgets & intents: Appex processes, widgets, Live Activities, Watch/tvOS extension points.
- Multiplatform Apple: iPadOS, macOS, tvOS focus engine, watchOS, visionOS.
- Performance & energy: Method, Instruments, MetricKit, SwiftUI cost, energy, app size.
- Testing: XCTest, Swift Testing, snapshots, UI tests, flakes.
- Debugging & Instruments: LLDB, sanitizers, logging, crash reports, repro, Xcode.
- Accessibility & localization: VoiceOver, Dynamic Type, contrast, RTL, i18n testing, shipping a11y.
- App Store & release engineering: Signing, CI/CD, versions, TestFlight, review, flags, release train.
- System design & staff+: Feature designs, reliability, multi-brand and SDKs, RFCs, estimation, org bets.
- Puzzles: “What does this print?” — teardown order, captures, defer, queues, actors, SwiftUI identity.
- Purchases & subscriptions: StoreKit 2, subscriptions, entitlements, server validation, paywalls, review rules.
- Coding rounds: Data structures in Swift, view-tree and geometry exercises, and timed machine-coding builds.