HCLTech IOS Developer Interview Questions and Answers

diff is used to compare two collections and return the differences, while guard is used for early exit in a function if a condition is not met.

• diff is a method used in Swift to compare two collections and return the differences.

• guard is a keyword used in Swift to provide an early exit from a function if a condition is not met.

• Example: let array1 = [1, 2, 3, 4], array2 = [3, 4, 5, 6]; let result = array1.diff(array2) //...read more

GCD stands for Grand Central Dispatch, a technology used in iOS for managing concurrent operations. Multithreading is the ability of a CPU to execute multiple threads concurrently.

• GCD is used for managing tasks asynchronously and efficiently utilizing system resources.

• Multithreading allows multiple tasks to run concurrently, improving performance and responsiveness of an application.

• Example: Using GCD to download image...read more

Serialisation in API is the process of converting data into a format that can be easily transmitted over a network.

• Serialisation is used to convert complex data structures into a format that can be easily transmitted over a network.

• It involves converting objects or data structures into a stream of bytes that can be sent over a network.

• JSON and XML are commonly used formats for serialising data in APIs.

• Serialisation is ...read more

Codable is a protocol in Swift that allows for easy encoding and decoding of data types to and from external representations.

• Codable protocol is used to convert custom data types to and from external representations such as JSON, plist, etc.

• It requires the types to conform to Encodable and Decodable protocols.

• Codable protocol provides default implementations for encoding and decoding.

• Example: struct Person: Codable { v...read more

MVVM is an architectural design pattern that separates the user interface code from the business logic and data model.

• MVVM stands for Model-View-ViewModel

• Model represents the data and business logic

• View displays the UI elements and interacts with the user

• ViewModel acts as a mediator between the Model and View, handling user inputs and updating the Model

• MVVM helps in achieving separation of concerns and making the code ...read more

Singletons can be thread-safe, but it depends on the implementation. Proper techniques must be used to ensure safety.

• Use dispatch_once in Objective-C for thread-safe singleton creation.

• In Swift, use a static constant to ensure thread safety.

• Example in Objective-C: + (instancetype)sharedInstance { static MyClass *sharedInstance; static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ sharedInstance = [[self a...read more

Guard let and if let are both used for optional binding in Swift, but they have different scopes and control flow behaviors.

• guard let is used for early exits; if the condition fails, it exits the current scope.

• if let allows you to safely unwrap optionals, but does not require an early exit.

• Example of guard let: guard let value = optionalValue else { return } // exits if optionalValue is nil.

• Example of if let: if let va...read more

Classes are reference types, while structs are value types in Swift.

• Classes are reference types, meaning they point to the same instance in memory when assigned to a new variable.

• Structs are value types, meaning they create a new copy when assigned to a new variable.

• Classes support inheritance, while structs do not.

• Classes can have deinitializers, while structs cannot.

• Example: class Person { var name: String } vs struc...read more

The Identifiable protocol in Swift provides a way to uniquely identify instances of a type.

• Conforms to Identifiable by implementing a 'var id: UUID { get }' property.

• Useful in SwiftUI for lists and dynamic views to track changes.

• Example: struct User: Identifiable { var id = UUID(); var name: String }

• Helps in differentiating between items in a collection.

I can join within 2 weeks of receiving an offer.

• I can start within 2 weeks of receiving an offer

• I need to give notice at my current job before starting

• I have some personal commitments that I need to wrap up before joining