IOS Developer Interview Questions for Freshers
1. What is iOS?
iOS is Apple’s mobile operating system that powers iPhones, iPads, and iPod Touch devices.
2. What are the key components of iOS app architecture?
- UIKit Framework
- Cocoa Touch Layer
- Media Layer
- Core Services Layer
3. Explain the MVC architecture in iOS.
Model-View-Controller is a design pattern used in iOS development where Model represents data and business logic, View represents the UI components, and Controller acts as an intermediary between Model and View.
4. What are optionals in Swift?
Optionals represent the absence of a value. They can either contain a value or be nil.
5. Explain the difference between let and var in Swift. let is used to declare constants, whereas var is used to declare variables whose values can be changed.
6. What is ARC in iOS development?
ARC (Automatic Reference Counting) automatically manages memory by keeping track of the references to objects in memory.
7. What is a delegate in iOS?
A delegate is an object that acts on behalf of another object, usually to handle events or data passing between objects.
8. What is the difference between frame and bounds in iOS?
frameis the rectangle that represents a view in its superview’s coordinate system.boundsis the rectangle that represents a view in its own coordinate system.
9. What is a closure in Swift?
A closure is a self-contained block of functionality that can be passed around and used in your code.
10. Explain the difference between synchronous and asynchronous tasks in iOS.
– Synchronous tasks block the current thread until they are completed.
– Asynchronous tasks allow the program to continue executing while the task is being performed in the background.
IOS Developer Interview Questions for Intermediate Level
11. What is CoreData and how is it used in iOS development?
CoreData is a framework provided by Apple to manage the model layer objects in an iOS application. It is used for data persistence.
12. Explain the concept of Storyboards in iOS development.
Storyboards are visual representations of the app’s user interface, allowing developers to design and configure multiple view controllers and their transitions in a single file.
13. What is Auto Layout and why is it used?
Auto Layout is a constraint-based layout system that allows developers to create user interfaces that dynamically adapt to different screen sizes and orientations.
14. What are protocols in Swift?
Protocols define a blueprint of methods, properties, and other requirements that can be adopted by a class, struct, or enum.
15. What is GCD (Grand Central Dispatch) and how is it used in iOS?
GCD is Apple’s framework for working with concurrent code. It provides a way to perform tasks concurrently and manage the execution of tasks in a multithreaded environment.
16. Explain the difference between a shallow copy and a deep copy.
– A shallow copy creates a new object that references the original object’s memory.
– A deep copy creates a new object and recursively copies all the objects referenced by the original object.
17. What is KVC (Key-Value Coding) in iOS?
KVC allows access to an object’s properties indirectly by specifying the property name as a string at runtime.
18. What is a singleton and how is it implemented in iOS?
A singleton is a design pattern that restricts the instantiation of a class to one object. It is implemented by providing a static method to access the single instance.
19. How do you handle memory management in iOS?
Memory management in iOS is primarily handled by ARC (Automatic Reference Counting), but developers need to be mindful of strong reference cycles and use weak references or unowned references where appropriate.
20. Explain the concept of generics in Swift.
Generics allow you to write flexible, reusable functions and types that can work with any type.
IOS Developer Interview Questions for Experienced Level
21. What are the advantages of using Core Animation in iOS development?
Core Animation provides hardware-accelerated rendering, which leads to smooth animations and improved performance.
22. How would you optimize the performance of an iOS app?
Performance optimization techniques include reducing CPU and memory usage, optimizing algorithms and data structures, and using instruments like Instruments and XCTest to identify bottlenecks.
23. Explain the concept of Keychain in iOS and why is it used?
Keychain is a secure storage mechanism provided by Apple for storing sensitive information such as passwords, cryptographic keys, and certificates.
24. What are the different types of app extensions in iOS?
– Today Extension
– Share Extension
– Action Extension
– Widget Extension
– Custom Keyboard Extension
– etc.
25. How do you handle background tasks in iOS?
Background tasks can be handled using Background Modes, Background Fetch, Push Notifications, or URLSession with Background Configuration.
26. Explain the concept of dependency injection in iOS development.
Dependency injection is a design pattern where the dependencies of an object are provided from outside rather than created internally. It helps improve testability and maintainability.
27. What are the different methods for data persistence in iOS?
– CoreData
– User Defaults
– Property Lists
– SQLite
– File System
– Keychain
– CloudKit
28. How would you implement secure communication between a client and a server in an iOS app?
Secure communication can be achieved using HTTPS with SSL/TLS encryption, certificate pinning, and proper handling of sensitive data.
29. What is the purpose of XCTest framework in iOS development?
XCTest is Apple’s framework for writing unit tests for iOS and macOS applications. It provides APIs for writing and running tests, as well as assertions for verifying expected behavior.
30. Explain the concept of Core Data concurrency types.
Core Data supports three concurrency types: Main Queue Concurrency, Private Queue Concurrency, and Main Queue Concurrency with Private Queue Concurrency for background tasks.