30+ IOS Developer Interview Questions and Answers for Freshers

Reference types store a reference to the actual data in memory, while value types store the actual data directly.

• Reference types are stored on the heap and passed by reference, while value types are stored on the stack and passed by value.

• Changing the value of a reference type will affect all references to that object, while changing the value of a value type will not affect other instances.

• Examples of reference types in iOS development include classes, while examples of valu...read more

To create a particular mobile screen, you need to design the layout using Interface Builder or programmatically in Swift.

• Design the UI layout using Interface Builder in Xcode

• Add necessary UI elements like labels, buttons, text fields, etc.

• Customize the appearance using constraints, auto layout, and size classes

• Implement functionality using Swift code to handle user interactions and data processing

Access controls/modifiers determine the visibility and accessibility of classes, methods, and properties in object-oriented programming.

• public access control allows a class, method, or property to be accessed from anywhere in the code

• open access control allows a class to be subclassed outside of the module where it is defined

• public is commonly used in Swift for most cases, while open is used when you want to allow subclassing from external modules

MVC focuses on separation of concerns, while MVP focuses on the interaction between components.

• MVC stands for Model-View-Controller, where the controller handles user input, the model manages the data, and the view displays the data.

• MVP stands for Model-View-Presenter, where the presenter acts as an intermediary between the model and the view, handling user input and updating the view.

• In MVC, the view has direct access to the model, while in MVP, the presenter mediates the co...read more

Property wrappers in Swift are used to add extra functionality to properties.

• Some types of property wrappers include @State, @Binding, @ObservedObject, @EnvironmentObject, @Published, @FetchRequest, @NSManaged, etc.

• Property wrappers help in managing the state of UI components, data flow, and data persistence in iOS apps.

• They provide a convenient way to encapsulate common behavior and logic for properties.

Swift 5 introduced ABI stability, improved performance, and new language features.

• ABI stability ensures compatibility between future Swift versions

• Improved performance with faster build times and reduced app size

• New language features include Result type, Raw strings, and Property wrappers

ARC (Automatic Reference Counting) is a memory management mechanism in Swift that automatically manages memory by keeping track of references to objects.

• ARC automatically deallocates objects when they are no longer referenced

• Retain cycles can occur if two objects hold strong references to each other

• Weak and unowned references are used to prevent retain cycles

I primarily use UIKit and SwiftUI frameworks for iOS development projects.

• Primary frameworks: UIKit, SwiftUI

• Additional frameworks: Core Data, Core Animation

• Examples: UIKit for building user interfaces, SwiftUI for declarative UI design

Types of memory management in iOS include Automatic Reference Counting (ARC) and Manual Reference Counting (MRC).

• Automatic Reference Counting (ARC) - manages memory automatically by keeping track of object references.

• Manual Reference Counting (MRC) - requires developers to manually manage memory by retaining and releasing objects.

• ARC is the default memory management system in iOS, while MRC is used in older codebases or when developers need more control over memory management...read more

Steps to add collection view in Swift.

• Create a UICollectionView instance

• Set the delegate and data source of the collection view

• Implement the required methods of UICollectionViewDataSource and UICollectionViewDelegate protocols

• Register the cell class or nib file for the collection view

• Return the number of items and configure the cell in the data source methods

• Implement any additional delegate methods as needed

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

• Swift is a modern, fast, and safe programming language.

• It is designed to work seamlessly with Apple's Cocoa and Cocoa Touch frameworks.

• Swift is used to develop applications for iOS, macOS, watchOS, and tvOS.

• It is open-source and has a large community of developers contributing to its growth.

• Swift is known for its concise syntax and powerful features like optionals, closures, and g...read more

Weak & Unowned references are used in ARC to prevent retain cycles in Swift programming.

• Weak references do not increase the retain count of an object, and automatically become nil when the object is deallocated.

• Unowned references do not keep a strong reference to the object, and can become a dangling pointer if the object is deallocated.

• ARC (Automatic Reference Counting) is a memory management system used in Swift to automatically manage memory for objects.

Environmental objects refer to physical entities in the environment that can be interacted with or manipulated by the user or application.

• Environmental objects can include items like trees, buildings, vehicles, and furniture in a virtual reality environment.

• These objects can be programmed to have specific behaviors or properties, such as collision detection or physics simulations.

• Interacting with environmental objects can enhance user immersion and engagement in the virtual e...read more

MVC architecture is a design pattern used in software development to separate the application into three main components: Model, View, and Controller.

• Model represents the data and business logic of the application.

• View is responsible for displaying the data to the user.

• Controller acts as an intermediary between Model and View, handling user input and updating the Model accordingly.

• MVC helps in organizing code, improving maintainability, and promoting reusability.

• Examples of M...read more

Retain cycle occurs when two objects hold a strong reference to each other, preventing them from being deallocated.

• Occurs in iOS development when two objects have strong references to each other

• Can lead to memory leaks as the objects are never deallocated

• Prevented by using weak or unowned references in Swift

Protocol Oriented Programming is a programming paradigm in Swift that focuses on defining protocols to define behavior.

• POP is a way of designing code by defining protocols that describe a set of behaviors.

• It encourages composition over inheritance, allowing for more flexible and reusable code.

• By using protocols, you can define a blueprint of methods and properties that a type must implement.

GCD (Grand Central Dispatch) is a concurrency framework that allows developers to perform tasks asynchronously.

• GCD is used to manage concurrent operations in iOS apps.

• It uses dispatch queues to manage tasks and execute them in parallel.

• GCD provides different types of queues such as serial, concurrent, and main queues.

• Example: DispatchQueue.main.async { // code to be executed on main queue }

• Example: DispatchQueue.global(qos: .userInitiated).async { // code to be executed on a ...read more

Publishers work by creating, distributing, and monetizing content through various channels.

• Publishers create content such as articles, videos, or apps.

• They distribute the content through platforms like websites, social media, or app stores.

• Publishers monetize their content through advertising, subscriptions, or in-app purchases.

SwiftUI is a user interface toolkit introduced by Apple for building apps across all Apple platforms using Swift programming language.

• Declarative syntax for building user interfaces

• Works seamlessly with Swift code

• Supports dynamic type, dark mode, localization, and accessibility

• Live preview feature for real-time UI updates

• Integrates with existing UIKit and AppKit views

Combine is a framework introduced by Apple for processing values over time.

• Combine is used for handling asynchronous events and data streams in Swift.

• It provides a declarative Swift API for processing values over time.

• Combine can be used for tasks like responding to user input, network requests, and more.

• It allows developers to work with asynchronous data streams in a more functional and reactive way.

• Example: Using Combine to handle network requests and update UI based on the...read more

Frame and bound are properties used in iOS development to define the position and size of a view within its superview.

• Frame refers to the view's position and size in its superview's coordinate system.

• Bound refers to the view's position and size in its own coordinate system, relative to its own top-left corner.

• Changing the frame will move the view within its superview, while changing the bound will not affect its position but may affect its content layout.

Struct and class are both used to define custom data types in Swift, but they have some key differences.

• Struct is a value type, while class is a reference type

• Structs are passed by value, while classes are passed by reference

• Classes support inheritance, while structs do not

• Classes have deinitializers, while structs do not

• Classes can have reference counting for memory management, while structs do not

Program to create a triangle using asterisks

• Use nested loops to print each row of the triangle

• Increment the number of asterisks printed in each row

• Example: for a triangle with 5 rows, the output would be: * , ** , *** , **** , *****

Autoclosure is a feature in Swift that automatically wraps an expression in a closure.

• Autoclosure is used to delay evaluation of an expression until it is actually needed.

• It is commonly used with functions that take closures as arguments, allowing the caller to pass in a regular value instead of a closure.

• Autoclosures are created by adding @autoclosure attribute before the closure's parameter type.

Completion handler is a closure that gets executed after a task is completed.

• Completion handlers are used to handle asynchronous tasks in iOS development.

• They are commonly used in network requests, animations, and other time-consuming tasks.

• Completion handlers take in parameters and return values, allowing for customization and flexibility.

• Example: URLSession.shared.dataTask(with: url) { data, response, error in // handle completion }

Implemented skills and features in IOS development.

• Proficient in Swift and Objective-C programming languages

• Experience with UIKit, Core Data, and Core Animation frameworks

• Implemented push notifications using Firebase Cloud Messaging

• Utilized RESTful APIs for data retrieval and storage

• Implemented in-app purchases and subscription services

Protocols define a blueprint of methods, properties, and other requirements that a class or struct must adopt. Closures are self-contained blocks of functionality that can be passed around and used in your code.

• Protocols define a set of methods, properties, and other requirements that a class or struct must implement.

• Closures are self-contained blocks of functionality that can capture and store references to any constants and variables from the context in which they are defin...read more

Fundamentals of iOS include UIKit, Core Data, Grand Central Dispatch, and Swift programming language.

• UIKit is the framework for building iOS user interfaces

• Core Data is the framework for managing data in iOS apps

• Grand Central Dispatch is used for managing concurrency and parallelism

• Swift is the primary programming language for iOS development

Swift is a powerful and modern programming language for iOS development, but it has its own set of advantages and disadvantages.

• Advantages: faster performance, safer code with optionals, easier to read and write code, interoperability with Objective-C

• Disadvantages: steep learning curve for beginners, limited community support compared to other languages like Java or Python

Concurrency is the ability of a system to execute multiple tasks simultaneously.

• Concurrency allows multiple tasks to run at the same time, improving performance and responsiveness.

• It can be achieved through techniques like multithreading and asynchronous programming.

• Concurrency is important in iOS development for tasks like networking, data processing, and UI updates.

My strengths include strong problem-solving skills, attention to detail, and a passion for learning new technologies.

• Strong problem-solving skills - I enjoy tackling complex issues and finding creative solutions.

• Attention to detail - I take pride in producing high-quality work with precision.

• Passion for learning new technologies - I am always eager to expand my knowledge and stay up-to-date with the latest advancements.

GCD (Grand Central Dispatch) is a concurrency framework in Swift that allows developers to perform tasks concurrently.

• GCD provides a way to execute tasks concurrently without managing threads manually.

• It uses queues to manage tasks and provides different types of queues like serial and concurrent queues.

• GCD simplifies the process of writing concurrent code by abstracting away the complexities of thread management.

• Example: DispatchQueue.main.async { // perform UI updates }

In iOS development, 'open' allows access to the class or method from any module, while 'public' restricts access to the current module only.

• Open access modifier allows classes and methods to be accessed from any module.

• Public access modifier restricts access to the current module only.

• Example: 'open class MyClass' can be accessed from any module, while 'public class MyClass' can only be accessed within the current module.

Weak - Strong Difference is a common interview question to assess understanding of object-oriented programming concepts.

• Weak references do not prevent the referenced object from being deallocated, while strong references do.

• Weak references are used to avoid retain cycles in iOS development.

• Strong references increase the retain count of an object, keeping it in memory until all strong references are released.