Swift
Apple's programming language for building native iOS, macOS, and watchOS apps — the primary skill for any iOS developer role.
Swift is Apple's modern programming language, introduced in 2014 to replace Objective-C as the standard for iOS and macOS development. It is the language behind virtually every native iPhone and iPad app, and iOS developer roles almost universally require Swift alongside UIKit or SwiftUI (Apple's declarative UI framework). Swift is strongly typed, fast, and designed for safety — it eliminates entire categories of bugs common in C-based languages. The iOS developer job market is consistently strong, and native Swift skills command a premium over cross-platform approaches.
Typical time to job-readiness: ~5 months.
Learning Swift
Beginner
Learn Swift syntax through Apple's free Swift Playgrounds app or 100 Days of SwiftUI (Paul Hudson's Hacking with Swift). Build a simple app with SwiftUI — a to-do list or weather app covers the core concepts: views, state, and data flow.
Intermediate
UIKit for legacy codebases (most companies still use it), networking with URLSession and Codable, persistence with Core Data or SwiftData, and navigation patterns. Learn how to integrate REST APIs and handle async code with async/await.
Advanced
Combine framework for reactive programming, app architecture (MVVM, TCA — The Composable Architecture), performance profiling with Instruments, and App Store submission. iOS interviews include a take-home project plus architecture discussion — be ready to defend your patterns.
Key concepts
- SwiftUI vs UIKit: SwiftUI is declarative (describe the UI), UIKit is imperative (build it step-by-step) — most companies use both
- @State, @Binding, @ObservableObject — SwiftUI's data ownership and binding system
- Optionals: Swift requires explicit handling of nil values to prevent crashes at compile time
- Protocols — Swift's primary abstraction mechanism; prefer protocol types to concrete types
- async/await for networking and background tasks; Combine for reactive data streams
- The App Store submission process: provisioning profiles, code signing, TestFlight, App Review
Common interview topics
- Explain the difference between value types (struct) and reference types (class) in Swift
- How does SwiftUI's state management work
- How do you handle networking and async code in Swift
- What is the difference between SwiftUI and UIKit — when would you use each
- Walk me through an app architecture pattern you've used (MVVM, VIPER, TCA)