iOS Development Cheat Sheet 2026

The 30 highest-yield iOS Development facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which SwiftUI container arranges views horizontally side by side? → HStack
2. Which iOS API is used to store small files in the app's sandboxed file system? → FileManager
3. What does `@IBOutlet` do in a UIKit view controller? → Creates a connection between a UI element in Interface Builder and a code property
4. What type of devices can run apps created with Swift? → IOS devices dating back to iOS 7 or later
5. What tool lets you test an iOS app on a virtual device without a physical iPhone? → Simulator
6. What does a SwiftUI Button require to respond to taps? → An action closure
7. What does ARC stand for in iOS memory management? → Automatic Reference Counting
8. What is a Core Data migration used for? → Updating the persistent store schema when the data model changes
9. What does a segue represent in a UIKit storyboard? → A transition between view controllers
10. Which symbol is used to mark a type as Optional in Swift? → ?
11. What does `@Binding` do in SwiftUI? → Creates a two-way connection to a state value owned by another view
12. Which UIKit class manages navigation between a stack of view controllers? → UINavigationController
13. What does `GeometryReader` do in SwiftUI? → Provides the size and coordinate space of the parent container to its child views
14. Which tool manages third-party Swift dependencies and is built into Xcode? → Swift Package Manager
15. Which Swift attribute marks a function that must be called with `try`? → throws
16. Which Xcode Instruments template is best suited for finding memory leaks in an iOS app? → Leaks
17. What is the purpose of `Identifiable` in SwiftUI `ForEach`? → Provides a stable identity so SwiftUI can track each item for efficient updates
18. What is the purpose of a UITableViewCell reuse identifier? → To efficiently recycle cells as they scroll off screen
19. Which UIKit class provides a reusable grid-based layout for views? → UICollectionView
20. In a UITableView, which method must you implement to provide the number of rows in a section? → numberOfRowsInSection
21. What is the main thread rule in UIKit? → All UI updates must be performed on the main thread
22. What is Core Data's primary role in an iOS app? → Object graph management and persistence to SQLite or other stores
23. Which actor type in Swift concurrency guarantees its code runs on the main thread? → MainActor
24. What is the purpose of UIGestureRecognizer? → Detect and respond to specific touch patterns like taps or swipes
25. Which Swift feature enables writing asynchronous code that reads like synchronous code? → async/await
26. What does enabling WAL mode in SQLite improve? → Concurrent read performance and write throughput
27. What is the role of `NSPredicate` in Core Data queries? → Filters fetch results based on specified conditions
28. Which SwiftUI modifier is used to respond when a view appears? → .onAppear
29. Which SwiftUI container arranges child views vertically? → VStack
30. Which Swift collection stores key-value pairs? → Dictionary