iOS Developer Interview Questions India 2026: Swift, SwiftUI and Architecture Guide

Optionals: the most fundamental Swift concept for interviews. Optional<T> wraps a value that might be nil. Optional chaining (?.) — access properties and call methods on optional values, returning nil if any step is nil. Nil coalescing (??) — provide a default value when an optional is nil. Forced unwrap (!) — crash at runtime if nil: only use when you are certain the value is non-nil (and explain this to interviewers, who look for awareness of the risk). Guard let vs if let: guard let unwraps an optional and exits the current scope if nil (preferred for early return patterns), if let unwraps for use only within the if block. Closures: value types that capture variables from their surrounding context. Memory management with closures: [weak self] in closures stored by the class (prevents retain cycles, self becomes optional), [unowned self] in closures guaranteed to outlive self (non-optional, crashes if self is already deallocated). Protocols and protocol-oriented programming: why Swift favours protocols over class inheritance (composition over inheritance, value types can conform to protocols, protocols can have default implementations via extensions). Generics: write code that works across multiple types with type-level constraints (<T: Equatable>).

Swift 5.5 (2021) introduced async/await and the structured concurrency model that replaced completion-handler callbacks. async functions can pause execution without blocking a thread (unlike DispatchQueue, which blocks a thread while waiting). await suspends the current task until the async operation completes. Task: creates a new concurrent unit of work. async let: runs multiple async operations concurrently and waits for all results. TaskGroup: dynamically spawns multiple tasks and collects results. Actors: reference types that protect their mutable state from concurrent access (no data races). Every method call on an actor is implicitly async (awaited by the caller). MainActor: the main thread actor, guaranteeing UI updates happen on the main thread (@MainActor annotation on a function or class). Interview question: 'Why did Apple introduce Actors when DispatchQueue.sync already serialises access?' Answer: actors provide compile-time data race safety (the Swift compiler prevents you from accessing actor-isolated state from outside the actor without await), while DispatchQueue serialisation is a runtime mechanism with no compile-time safety.

UIKit (2008, still used in 95% of iOS codebases): imperative, event-driven, view controller lifecycle. Key lifecycle methods: viewDidLoad (called once, view hierarchy created in memory), viewWillAppear (called every time the view becomes visible), viewDidAppear (view is on screen and animated in), viewWillDisappear and viewDidDisappear (reverse sequence). UIViewController responsibilities: hold references to UIViews, respond to user interactions via IBActions, manage data flow via delegates and notifications. Auto Layout: NSLayoutConstraint for declarative layout. SwiftUI (2019, iOS 13+, declarative): body property returns a View tree. @State for local view state (triggers body recomputation on change). @Binding for two-way data flow from parent to child. @ObservedObject for external reference-type data sources. @StateObject for owning an ObservableObject instance (initialised only once per view lifecycle). @EnvironmentObject for dependency injection through the view hierarchy. Interop: UIViewRepresentable wraps a UIKit view for use in SwiftUI. 2026 reality: most companies use both, SwiftUI for new screens, UIKit for legacy migration.

MVVM for iOS: ViewModel (observes data from repository, publishes UI state via @Published or AsyncStream), View (subscribes to ViewModel state, sends user actions to ViewModel), Repository (abstracts network and local persistence from ViewModel). Clean Architecture: ViewModel calls Use Cases (pure business logic), Use Cases call Repositories. Coordinator pattern for navigation: Coordinator object owns UINavigationController and handles all push/pop/modal logic, decoupling navigation from ViewControllers. Interview question: 'How would you structure the Swiggy iOS app for the order tracking feature, from API call to UI update?' Expected answer: API call in a Repository (OrderTrackingRepository), parsing into domain model (Order), business logic in a Use Case (GetLiveOrderStatusUseCase), ViewModel subscribes and publishes status to View via @Published, View renders status UI and updates the map. iOS developer salary India 2026: junior (0-2 years): Rs 10-25 LPA at product companies. Mid-level (2-5 years): Rs 25-60 LPA. Senior (5-8 years): Rs 55-100 LPA. Cross-platform premium (Swift plus Kotlin): Rs 15-30% above single-platform. Top iOS hiring companies: Swiggy, PhonePe, Myntra, CRED, Zepto, Ola, Nykaa, Google India, Atlassian India, Adobe India.