iOS Interview Questions and Answers for Freshers

Are you a fresher preparing for an iOS developer interview? If so, you’re likely eager to showcase your knowledge and skills in iOS development. To help you ace your interview, we’ve compiled a list of the top iOS interview questions and answers.

Q1. What is ARC in iOS?

Ans: ARC stands for Automatic Reference Counting. It’s a memory management technique used in iOS to automatically manage memory by keeping track of objects’ references.

Q2. What are the key features of Swift programming language?

Ans: Swift is known for its safety, speed, modern syntax, optionals, type inference, and memory management using Automatic Reference Counting (ARC).

Q3. Explain the difference between strong, weak, and unowned references in Swift.

Ans: Strong references keep objects alive as long as there’s at least one strong reference to them. Weak references don’t keep objects alive and automatically become nil when the object they reference is deallocated. Unowned references are similar to weak references but don’t require unwrapping and are used when it’s guaranteed that the referenced object won’t be deallocated before the reference is accessed.

Q4. What is the difference between a delegate and a notification in iOS?

Ans: A delegate is a design pattern used for one-to-one communication between objects, where one object acts on behalf of another object. Notifications, on the other hand, are used for one-to-many communication, allowing an object to broadcast messages to multiple observers without knowing who they are.

Q5. What is a closure in Swift?

Ans: A closure is a self-contained block of functionality that can be passed around and used in your code. It captures references to variables and constants from the surrounding context in which it’s defined.

Q6. Explain the concept of optional chaining in Swift.

Ans: Optional chaining is a process for querying and calling properties, methods, and subscripts on an optional that might currently be nil. If the optional contains a value, the property, method, or subscript call succeeds; if the optional is nil, the call returns nil.

Q7. What are generics in Swift?

Ans: Generics are a way to make your code more flexible and reusable by writing code that doesn’t depend on specific types. They allow you to write functions and types that can work with any type.

Q8. What are the advantages of using Swift over Objective-C?

Ans: Swift offers modern syntax, type inference, optionals, memory management with ARC, safety features like nil safety and type safety, and improved performance over Objective-C.

Q9. What are the different layers of the iOS architecture?

Ans: The iOS architecture consists of four main layers: Cocoa Touch layer, Media layer, Core Services layer, and Core OS layer.

Q10. What is the difference between synchronous and asynchronous tasks in iOS?

Ans: Synchronous tasks block the current thread until they complete, while asynchronous tasks allow the thread to continue executing other tasks while they’re in progress.

Q11. Explain the concept of GCD (Grand Central Dispatch) in iOS.

Ans: GCD is a low-level API provided by Apple for managing concurrent operations in iOS. It allows you to perform tasks concurrently and in parallel, improving the performance and responsiveness of your app.

Q12. What is the difference between viewDidLoad and viewWillAppear in iOS?

Ans: viewDidLoad is called when the view controller’s view hierarchy is loaded into memory, while viewWillAppear is called just before the view controller’s view is added to the view hierarchy and displayed on the screen.

Q13. What is Core Data in iOS?

Ans: Core Data is a framework provided by Apple for managing the model layer objects in iOS applications. It allows you to store, retrieve, and manipulate data in a database-like structure.

Q14. Explain the concept of protocols in Swift.

Ans: Protocols are a way to define a blueprint of methods, properties, and other requirements that a class, structure, or enumeration must adopt in order to conform to the protocol. They enable you to define a common interface that multiple types can adhere to.

Q15. What is the purpose of the guard statement in Swift?

Ans: The guard statement is used to provide early exit from a function, method, or loop if a condition isn’t met. It helps improve code readability by reducing the need for nested if statements and ensuring that certain conditions are met before proceeding with execution.

Q16. What is the difference between a value type and a reference type in Swift?

Ans: A value type is a type whose value is copied when it’s assigned to a variable or passed as an argument to a function, while a reference type is a type whose value is shared when it’s assigned to a variable or passed as an argument to a function. Structs and enums are examples of value types, while classes are examples of reference types.

Q17. What is the purpose of the didSet property observer in Swift?

Ans: The didSet property observer is used to observe and respond to changes in the value of a property. It’s called immediately after the new value is stored, allowing you to perform additional actions or validation based on the new value.

Q18. Explain the concept of method swizzling in iOS.

Ans: Method swizzling is a technique used to dynamically change the implementation of a method at runtime. It involves swapping the implementation of one method with another, allowing you to modify the behavior of existing methods or add new functionality to existing classes.

Q19. What is the purpose of UserDefaults in iOS?

Ans: UserDefaults is a simple key-value store provided by Apple for storing small pieces of data such as user preferences, settings, and app state. It’s commonly used for storing user settings and preferences that persist across app launches.

Q20. Explain the difference between a push notification and a local notification in iOS.

Ans: A push notification is a message sent from a remote server to the user’s device, typically used to notify the user about updates, messages, or events from a remote service or app. A local notification, on the other hand, is scheduled and delivered by the app itself, without the need for a remote server. It’s used to notify the user about events or reminders within the app.

Q21. What is Core Animation in iOS?

Ans: Core Animation is a graphics rendering and animation infrastructure provided by Apple for iOS and macOS. It allows you to create smooth, fluid animations and transitions in your app’s user interface.

Q22. What is Auto Layout in iOS?

Ans: Auto Layout is a constraint-based layout system provided by Apple for designing user interfaces in iOS and macOS. It allows you to create adaptive and flexible user interfaces that automatically adjust to different screen sizes and orientations.

Q23. What is the purpose of the AppDelegate class in iOS?

Ans: The AppDelegate class is the entry point for an iOS app and is responsible for managing the app’s lifecycle, handling system events, and coordinating the app’s overall behavior. It contains methods for responding to various system events such as app launch, termination, and background execution.

Q24. Explain the concept of memory management in iOS.

Ans: Memory management in iOS involves managing the allocation and deallocation of memory for objects in your app. iOS uses Automatic Reference Counting (ARC) to automatically manage memory by keeping track of objects’ references and deallocating them when they’re no longer needed.

Summary

iOS interview questions and answers, you’ll be well-prepared to showcase your knowledge and skills in iOS development during your next interview. Read more: Online Interview Questions