Here are the interview questions and answers for Swift Developer Jobs in the USA;

1. What is Swift?

   • Swift is a powerful and intuitive programming language developed by Apple for iOS, macOS, watchOS, and tvOS app development.

2. Explain Optionals in Swift.

   • Optionals represent the absence of a value in Swift. They allow variables to have a “no-value” state.

3. What is the difference between let and var in Swift?

   • let is used for constant values (immutable), while var is used for variables (mutable).

4. What is the significance of guard statements?

   • Guard statements are used for early exit from a function if a certain condition is not met, helping to improve code readability.

5. What is the Swift Codable protocol?

   • Codable is a protocol in Swift used for encoding and decoding data to and from JSON.

6. Explain the concept of ARC (Automatic Reference Counting) in Swift.

   • ARC automatically manages memory by keeping track of the number of references to an object and deallocating it when the count drops to zero.

7. What is the difference between a class and a struct in Swift?

   • Classes are reference types, and structs are value types. Classes support inheritance, while structs do not.

8. How does Swift handle memory management compared to Objective-C?

   • Swift uses Automatic Reference Counting (ARC) for memory management, eliminating the need for manual memory management found in Objective-C.

9. What is the purpose of the init method in Swift?

   • The init method is used to initialize an instance of a class or structure in Swift.

10. What are closures in Swift?

    • Closures are self-contained blocks of functionality that can be passed around and used in your code.

11. Explain the concept of option chaining.

    • Option chaining is a way to call properties, methods, and subscripts on an optional that might currently be nil.

12. What is the difference between a protocol and a delegate in Swift?

    • A protocol defines a blueprint of methods, properties, and other requirements, while a delegate is an object that implements the protocol to provide specific functionality.

13. How does Swift handle error handling?

    • Swift uses a combination of the try, catch, and throw keywords for error handling.

14. What is the Swift type inference feature?

    • Type inference allows the Swift compiler to deduce the data type of a variable based on its initial value.

15. What is the @escaping keyword in Swift?

    • The @escaping keyword is used to indicate that a closure is allowed to outlive the scope in which it was defined.

16. What is the purpose of the lazy keyword in Swift?

    • The lazy keyword is used to delay the initialization of a property until it is accessed for the first time.

17. Explain the concept of generics in Swift.

    • Generics allow you to write flexible and reusable functions and types that can work with any type.

18. What is the purpose of the self keyword in Swift?

    • self is used to refer to the instance of the current type or to differentiate between instance variables and method parameters.

19. How does Swift handle multiple inheritance?

    • Swift does not support multiple inheritance for classes, but it allows the adoption of multiple protocols.

20. What is a didSet observer in Swift?

    • didSet is an observer that is called after a property’s value is set. It is used to perform actions when a property changes.

21. Explain the concept of type casting in Swift.

    • Type casting is a way to check the type of an instance or to treat it as a different type.

22. What is the Swift main queue and why is it important?

    • The main queue is the primary queue in Swift for UI-related tasks, ensuring that UI updates occur on the main thread to avoid concurrency issues.

23. How does Swift handle concurrency?

    • Swift introduces the async and await keywords to simplify and enhance concurrency through asynchronous programming.

24. What is the purpose of the didSet observer in Swift?

    • The willSet observer is called just before the value of a property is set. It is used to take action before a property changes.

25. Explain the concept of dependency injection in Swift.

    • Dependency injection is a design pattern in Swift where the dependencies of an object are provided from the outside rather than created within the object. It promotes modularity and testability in code.