Landing your dream job as an iOS developer often hinges on how well you navigate the swift interview questions that come your way. Proper preparation is key. Mastering commonly asked swift interview questions significantly boosts your confidence, clarifies your thinking, and dramatically improves your overall interview performance. This guide will equip you with the knowledge to excel.

What are swift interview questions?

Swift interview questions are designed to assess a candidate's understanding of the Swift programming language, iOS development principles, and related technologies. These questions typically cover fundamental concepts like data types, control flow, object-oriented programming, memory management, and concurrency. They also delve into frameworks like SwiftUI and UIKit, as well as specific areas like networking, data persistence, and UI design. The purpose of swift interview questions is to evaluate a candidate's technical proficiency, problem-solving skills, and practical experience in building iOS applications. Being well-prepared for these swift interview questions is crucial for any aspiring iOS developer.

Why do interviewers ask swift interview questions?

Interviewers use swift interview questions to gauge a candidate's suitability for an iOS developer role. They aim to assess not just theoretical knowledge but also the ability to apply that knowledge to real-world problems. Through swift interview questions, interviewers evaluate technical competence, problem-solving ability, familiarity with iOS development best practices, and the capacity to learn and adapt to new technologies. They also look for indicators of practical experience, such as previous projects, contributions to open-source initiatives, or personal app development endeavors. Ultimately, swift interview questions help interviewers determine whether a candidate possesses the skills and experience necessary to contribute effectively to an iOS development team. You'll want to use Verve AI’s Interview Copilot to simulate a real interview and practice how to answer these questions.

Here’s a preview of the 30 swift interview questions we’ll cover:

1. What is Swift primarily used for in programming?

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

3. What are Enumerations (Enums) in Swift?

4. What is a lazy property in Swift?

5. What is the guard statement and its benefits?

6. How do you define an optional property in Swift?

7. What is Key-Value Coding (KVC)?

8. What are the essential certificates needed for iOS app development?

9. What is reuseIdentifier used for in iOS?

10. How does Swift handle exceptions?

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

12. Explain how closures work in Swift.

13. How is memory managed in Swift?

14. What is SwiftUI?

15. What is the difference between @State and @Binding in SwiftUI?

16. How do you manage data flow in SwiftUI?

17. What is the role of UIViewController in iOS?

18. What are tuples in Swift?

19. Explain how Swift supports protocol-oriented programming.

20. What’s the difference between synchronous and asynchronous code in Swift?

21. What are property observers in Swift?

22. How do you create animations in SwiftUI?

23. What are the new features in Swift 4?

24. What is TVMLKit?

25. How do you handle memory leaks in Swift?

26. What is the difference between weak and unowned references?

27. What is the difference between frame and bounds in UIKit?

28. What is the significance of @objc in Swift?

29. How do UI elements work in iOS?

30. Who calls the main app function during the app launch cycle?

Now, let's dive into each of these swift interview questions in detail.

## 1. What is Swift primarily used for in programming?

Why you might get asked this:

This question assesses your fundamental understanding of Swift's purpose and its place in the Apple ecosystem. Interviewers want to know if you grasp the core applications of Swift, which is critical for any iOS developer role. This is one of the most basic swift interview questions.

How to answer:

Start by stating that Swift is Apple's modern programming language. Emphasize its primary use for developing applications across Apple's platforms: iOS, macOS, watchOS, and tvOS. Mention its key features, such as safety, speed, and modern syntax, which make it a preferred choice for Apple development.

Example answer:

"Swift is Apple's powerful and intuitive programming language designed primarily for building apps across all Apple platforms. So that includes iOS, macOS, watchOS, and tvOS. It's favored because it's safe, performs quickly, and has a modern syntax, making it a really effective tool for Apple-centric development. I think that background really underscores why I focus on Swift in my projects."

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

Why you might get asked this:

Understanding the difference between let and var is crucial for writing correct and efficient Swift code. It demonstrates your grasp of immutability and mutability, which are essential for managing data effectively and avoiding unexpected side effects. This is a fundamental concept tested in many swift interview questions.

How to answer:

Clearly explain that let declares constants, meaning their values cannot be changed after initialization. Conversely, var declares variables, whose values can be modified throughout the program. Provide a simple example to illustrate the difference. Explain how using let when possible improves code safety and predictability.

Example answer:

"The key difference is mutability. let declares a constant, so once you assign a value, it can't be changed. var declares a variable, which means you can modify its value as needed. In a project I worked on, I used let for things like API keys that shouldn't change and var for things like user input that would need updating. That helped ensure that the key configurations remained consistent."

## 3. What are Enumerations (Enums) in Swift?

Why you might get asked this:

Enums are a powerful feature in Swift for defining a type with a limited set of possible values. This question assesses your understanding of how to create type-safe code and manage related values effectively. It’s a common topic in swift interview questions.

How to answer:

Define enums as a way to group related values under a common type. Explain that enums in Swift can have associated values and methods, making them more versatile than in some other languages. Provide an example, such as an enum representing the days of the week.

Example answer:

"Enums in Swift are a way to define a type that can be one of several predefined values, which is super useful for type safety. Unlike some other languages, Swift enums can also have associated values and even methods. For example, in a weather app, I might use an enum to define the different weather conditions like sunny, cloudy, or rainy, and each case could have associated values like temperature or precipitation level. This makes the code much cleaner and easier to manage."

## 4. What is a lazy property in Swift?

Why you might get asked this:

Lazy properties are an optimization technique that defers initialization until the property is actually needed. This question tests your knowledge of performance optimization strategies in Swift and your ability to write efficient code.

How to answer:

Explain that a lazy property's initial value is not calculated until the first time it is accessed. Highlight that this is useful when the initial value depends on complex or resource-intensive setup. Provide an example of when using a lazy property would be beneficial, such as when the property depends on another instance property that is not yet initialized.

Example answer:

"A lazy property is one whose initial value isn't calculated until it's actually used for the first time, which can really help with performance. It's especially useful when the property's initial value depends on something that might not be available right away, or if calculating it is resource-intensive. I used it once when creating a complex UI element that was only needed under certain conditions. By making it lazy, I avoided the overhead of creating it unless it was actually necessary."

## 5. What is the guard statement and its benefits?

Why you might get asked this:

The guard statement is a powerful tool for improving code readability and handling error conditions early in a function. This question assesses your ability to write clean and maintainable Swift code. Understanding guard statements is important for addressing swift interview questions.

How to answer:

Explain that the guard statement is used for early exits in functions when certain conditions are not met. Highlight its benefits, such as improved readability by avoiding nested if let statements and ensuring that certain conditions are met before continuing execution. Provide an example of how to use a guard statement to unwrap an optional.

Example answer:

"The guard statement is essentially a conditional check that lets you exit a function early if certain conditions aren't met, which is great for code clarity. It's especially useful for unwrapping optionals and making sure you have the data you need before proceeding. For example, instead of nesting if let statements, you can use guard let to unwrap an optional and, if it's nil, exit the function immediately. This really cleans up the code and makes it easier to read."

## 6. How do you define an optional property in Swift?

Why you might get asked this:

Optionals are a fundamental concept in Swift that addresses the possibility of a variable having no value. This question tests your understanding of how to handle nil values safely and prevent runtime errors.

How to answer:

Explain that you add a question mark ? after the type to declare a property as optional. Emphasize that this means the property can either hold a value or be nil. Explain the importance of unwrapping optionals safely before using their values.

Example answer:

"To define an optional property in Swift, you just add a question mark after the type. For example, var name: String?. This means that the name property can either hold a string value or be nil. It's a really important concept because it allows you to handle cases where a value might be missing, which helps prevent runtime errors. When you use an optional, you need to safely unwrap it to access its value, usually with if let or guard let."

## 7. What is Key-Value Coding (KVC)?

Why you might get asked this:

Key-Value Coding (KVC) is a mechanism for accessing an object's properties indirectly using strings. While less common in modern Swift, it's still relevant due to its use in older Objective-C APIs and dynamic programming patterns.

How to answer:

Explain that KVC is a mechanism for accessing an object's properties using strings to identify them. Mention that it's useful for dynamic programming patterns in iOS, such as accessing properties at runtime. Acknowledge that while it's less common in pure Swift, it's still relevant for interoperability with Objective-C code.

Example answer:

"Key-Value Coding, or KVC, is a way to access an object's properties indirectly using strings. So, instead of directly accessing a property like myObject.name, you'd use a string to refer to the name property. It's particularly useful for dynamic programming patterns, like when you need to access properties at runtime. Although KVC isn't as common in modern Swift because of its type safety features, it’s still relevant when you're working with older Objective-C APIs or when you need that level of dynamic access."

## 8. What are the essential certificates needed for iOS app development?

Why you might get asked this:

Understanding code signing and provisioning is crucial for deploying iOS apps to devices and the App Store. This question tests your knowledge of the certificates required for different stages of the development process.

How to answer:

Identify the essential certificates, including the Development Certificate (for testing on devices) and the Distribution Certificate (for App Store submission). Briefly explain the purpose of each certificate and how they are used in the code signing process.

Example answer:

"The essential certificates for iOS app development are primarily the Development Certificate and the Distribution Certificate. The Development Certificate lets you test your app on physical devices during development. The Distribution Certificate, on the other hand, is what you need to submit your app to the App Store. These certificates are part of the code signing process, which ensures that your app is trusted and hasn't been tampered with."

## 9. What is reuseIdentifier used for in iOS?

Why you might get asked this:

The reuseIdentifier is a key optimization technique for UITableView and UICollectionView. This question assesses your understanding of how to improve performance and memory usage in iOS apps with scrolling lists.

How to answer:

Explain that reuseIdentifier is used in UITableView and UICollectionView to reuse rows or cells efficiently. Highlight that by grouping similar cells under the same identifier, the system can reuse existing cells instead of creating new ones, improving memory usage and scrolling performance.

Example answer:

"reuseIdentifier is used in UITableView and UICollectionView to efficiently reuse cells. When a cell scrolls off-screen, instead of being deallocated, it’s placed in a queue. Then, when a new cell needs to be displayed, the table view or collection view first checks if there's a reusable cell available with the correct reuseIdentifier. This avoids the overhead of creating new cells all the time, which really boosts performance, especially in long lists."

## 10. How does Swift handle exceptions?

Why you might get asked this:

Error handling is a critical aspect of writing robust and reliable Swift code. This question assesses your understanding of how to manage errors gracefully and prevent app crashes.

How to answer:

Explain that Swift uses try, catch, and throw for error handling. Describe how you can define custom error types using enums that conform to the Error protocol. Provide an example of how to use a do-catch block to handle potential errors.

Example answer:

"Swift handles exceptions, or rather errors, using try, catch, and throw. You can define custom error types using enums that conform to the Error protocol. To handle a potential error, you wrap the code that might throw an error in a do block, and then you use catch blocks to handle specific errors. For instance, if you're reading a file, you can use a do-catch block to handle errors like the file not existing or not having permissions. It helps you manage errors gracefully without crashing the app."

## 11. What is the main difference between a class and a struct in Swift?

Why you might get asked this:

Understanding the difference between classes and structs is fundamental to Swift programming. This question assesses your knowledge of value types vs. reference types and their implications for memory management and data sharing.

How to answer:

Clearly explain that classes are reference types and support inheritance, while structs are value types and do not support inheritance. Emphasize that structs are copied when assigned or passed, whereas classes are passed by reference. Discuss the implications of these differences for memory management and data sharing.

Example answer:

"The main difference is that classes are reference types, and structs are value types. Classes support inheritance, which means one class can inherit properties and methods from another. Structs don't support inheritance. When you assign or pass a struct, it's copied, so you get a brand new instance. With classes, you're passing a reference, so multiple variables can point to the same instance. This has implications for memory management and how you share data. For example, if you want to make sure that changes to one instance don't affect others, you'd use a struct."

## 12. Explain how closures work in Swift.

Why you might get asked this:

Closures are self-contained blocks of functionality that can be passed around and used in your code. They are a powerful feature in Swift for writing concise and flexible code.

How to answer:

Explain that closures are self-contained blocks of functionality that can be passed around and used in code. Mention that they can capture and store references to variables and constants from the context in which they are defined. Provide an example of using a closure to sort an array.

Example answer:

"Closures are essentially self-contained blocks of code that can be passed around and used in your code. They can capture and store references to variables and constants from the surrounding context, which makes them really powerful. For example, you can use a closure to sort an array. The closure would define the sorting logic, and you can pass it to the sorted(by:) method. It's like having a mini-function that you can pass around."

## 13. How is memory managed in Swift?

Why you might get asked this:

Memory management is a crucial aspect of iOS development. This question assesses your understanding of how Swift manages memory automatically and how to avoid memory leaks.

How to answer:

Explain that Swift uses Automatic Reference Counting (ARC) to track and manage the memory usage of instances. Describe how ARC automatically deallocates instances when there are no more references to them. Mention the importance of avoiding strong reference cycles to prevent memory leaks.

Example answer:

"Swift uses Automatic Reference Counting, or ARC, to manage memory. ARC automatically tracks and manages the memory used by instances of classes. When there are no more strong references to an instance, ARC deallocates the memory that was used by that instance. It's pretty hands-off, but you do need to be careful about strong reference cycles, which can cause memory leaks. Basically, ARC handles the memory management for you, but you need to write code that doesn’t create reference cycles."

## 14. What is SwiftUI?

Why you might get asked this:

SwiftUI is Apple's modern UI framework for building user interfaces across all Apple platforms. This question tests your knowledge of this declarative framework and its benefits over traditional UIKit.

How to answer:

Explain that SwiftUI is Apple's declarative UI framework for building user interfaces across all Apple platforms using Swift code. Highlight its key features, such as a reactive programming model and state-driven views. Mention its benefits, such as simplified UI development and live previews.

Example answer:

"SwiftUI is Apple’s modern, declarative UI framework that allows you to build user interfaces across all Apple platforms using Swift. It simplifies UI development with a reactive programming model, where you describe the UI's desired state, and SwiftUI automatically updates the view when the state changes. It also has live previews, which make it much easier to see your changes in real-time. I find it more intuitive than UIKit and it allows for much faster development cycles."

## 15. What is the difference between @State and @Binding in SwiftUI?

Why you might get asked this:

@State and @Binding are fundamental property wrappers in SwiftUI for managing state and data flow. This question assesses your understanding of how to use them correctly to build dynamic and interactive UIs.

How to answer:

Explain that @State is used for a source of truth owned by a view, while @Binding creates a two-way connection to a value owned by a parent view. Emphasize that @State is for local state within a view, while @Binding is for sharing state between views.

Example answer:

"@State and @Binding are both property wrappers in SwiftUI used for managing data, but they have different purposes. @State is used for local state that's owned and managed by a single view. @Binding, on the other hand, creates a two-way connection to a value that's owned by a parent view. So, if a child view needs to modify a value that's owned by its parent, you'd use @Binding. It ensures that changes in the child view are reflected in the parent view and vice versa."

## 16. How do you manage data flow in SwiftUI?

Why you might get asked this:

Data flow is a critical aspect of building complex SwiftUI applications. This question assesses your understanding of the different tools and techniques available for managing data and keeping your UI updated.

How to answer:

Explain that SwiftUI uses data bindings, state properties (@State), observable objects (@ObservedObject), and environment objects (@EnvironmentObject) to manage data flow reactively. Describe how each of these tools is used to keep the UI updated when the underlying data changes.

Example answer:

"SwiftUI uses a few different mechanisms to manage data flow and keep the UI updated. There are data bindings, state properties using @State, observable objects with @ObservedObject, and environment objects using @EnvironmentObject. @State is for simple, local state within a view. Observable objects are classes that can publish changes, and @ObservedObject is used to observe those changes in a view. Environment objects are used to share data across the entire app. The key is that when the data changes, SwiftUI automatically updates the UI, which makes it super reactive and easy to manage." Want to simulate a real interview? Verve AI lets you rehearse with an AI recruiter 24/7. Try it free today at https://vervecopilot.com.

## 17. What is the role of UIViewController in iOS?

Why you might get asked this:

UIViewController is a fundamental class in UIKit that manages a view hierarchy. This question assesses your understanding of the traditional UIKit framework and its role in building iOS apps.

How to answer:

Explain that UIViewController manages a view hierarchy in iOS apps. Describe its responsibilities, such as loading views, handling rotation, and responding to system events. Mention that it's the foundation for building complex UIs in UIKit.

Example answer:

"UIViewController is a fundamental class in UIKit that manages a view hierarchy for a specific part of your app's interface. It's responsible for loading the views, handling device rotation, and responding to system events like memory warnings. Every screen or section of your app typically has its own UIViewController to manage the views and data associated with it. It is really the backbone of how you structure your UI in UIKit."

## 18. What are tuples in Swift?

Why you might get asked this:

Tuples are a simple way to group multiple values into a single compound value. This question tests your understanding of how to use tuples to return multiple values from a function or to group related data.

How to answer:

Explain that tuples group multiple values into a single compound value. Emphasize that each value in a tuple can be of a different type and accessed by position or name. Provide an example of how to use a tuple to return multiple values from a function.

Example answer:

"Tuples are a way to group multiple values into a single compound value. Each value in a tuple can be of a different type. You can access the values in a tuple by their position, like tuple.0, tuple.1, or by name if you give them names when you create the tuple. They are often used to return multiple values from a function. For example, you might return a tuple containing a status code and a message from a network request."

## 19. Explain how Swift supports protocol-oriented programming.

Why you might get asked this:

Protocol-oriented programming is a key paradigm in Swift that promotes flexibility and code reuse. This question assesses your understanding of how to use protocols to define interfaces and build decoupled code.

How to answer:

Explain that Swift's protocols define interfaces or blueprints of methods and properties. Highlight that protocol-oriented programming encourages designing flexible, reusable, and decoupled code by using protocols instead of inheritance. Mention that protocols can be adopted by classes, structs, and enums.

Example answer:

"Swift fully supports protocol-oriented programming, which is a paradigm that focuses on defining interfaces or blueprints using protocols. These protocols define a set of methods and properties that conforming types must implement. Protocol-oriented programming encourages designing flexible, reusable, and decoupled code because you can use protocols instead of relying heavily on inheritance. Classes, structs, and enums can all adopt protocols, which allows you to write more generic and adaptable code. It’s great for creating modular and testable systems."

## 20. What’s the difference between synchronous and asynchronous code in Swift?

Why you might get asked this:

Understanding concurrency and asynchronous programming is crucial for building responsive iOS apps. This question assesses your knowledge of how to perform tasks in the background without blocking the main thread.

How to answer:

Explain that synchronous code runs sequentially, blocking the thread until it finishes. In contrast, asynchronous code runs concurrently, allowing other operations to execute while waiting for a task to complete. Mention that asynchronous code is often implemented with closures, completion handlers, or Swift's async/await.

Example answer:

"Synchronous code executes sequentially, meaning each operation has to complete before the next one starts, which can block the thread. Asynchronous code, on the other hand, allows multiple operations to run concurrently. It doesn't block the thread, so other tasks can execute while waiting for a task to complete. You typically implement asynchronous code using closures, completion handlers, or with Swift’s async/await. For example, when fetching data from a network, you would use asynchronous code so that the UI doesn't freeze while waiting for the response."

## 21. What are property observers in Swift?

Why you might get asked this:

Property observers allow you to respond to changes in a property's value. This question assesses your understanding of how to use willSet and didSet to execute code before or after a property changes.

How to answer:

Explain that property observers (willSet and didSet) observe and respond to changes in a property's value. Describe how willSet is called before the value changes, and didSet is called after the value changes. Provide an example of using property observers to update the UI when a data model changes.

Example answer:

"Property observers in Swift, like willSet and didSet, let you observe and respond to changes in a property’s value. willSet is called just before the property's value is set, and didSet is called immediately after the new value is set. Inside willSet, you can access the new value via newValue, and inside didSet, you can access the old value via oldValue. These are useful for triggering updates or side effects whenever a property changes. For example, you might use didSet to update the UI when a data model changes."

## 22. How do you create animations in SwiftUI?

Why you might get asked this:

Animations are a key part of creating engaging user experiences in iOS apps. This question assesses your understanding of how to use SwiftUI's animation APIs to bring your UI to life.

How to answer:

Explain that animations can be created using the .animation() modifier on views or by changing state properties that bind to the view and cause it to animate implicitly or explicitly. Provide an example of how to animate a view's opacity when a button is tapped.

Example answer:

"In SwiftUI, you can create animations by using the .animation() modifier on views or by changing state properties that are bound to the view. When you change a state property, and the view depends on that property, SwiftUI can automatically animate the change. You can also explicitly define animations using the withAnimation block. For example, if you want to animate a view's opacity when a button is tapped, you can use the .animation() modifier on the opacity property and then change the state property that controls the opacity."

## 23. What are the new features in Swift 4?

Why you might get asked this:

Staying up-to-date with the latest Swift features is important for writing modern and efficient code. This question assesses your knowledge of the key improvements introduced in Swift 4.

How to answer:

Mention that Swift 4 introduced faster Unicode-compliant strings, multiple return values with tuples, native error handling with throw/try/catch, and improved serialization with Codable protocol. Highlight the benefits of these features, such as improved performance, better error handling, and easier data serialization.

Example answer:

"Swift 4 introduced a lot of great features. Some of the key ones include faster and more Unicode-compliant strings, which improved text processing performance. There were also improvements to tuples, allowing for multiple return values from functions, which made code cleaner. Native error handling with throw, try, and catch was enhanced, and the Codable protocol was introduced for easier serialization and deserialization of data. These updates made the language more robust and easier to use."

## 24. What is TVMLKit?

Why you might get asked this:

TVMLKit is a framework for building Apple TV apps using TVML and JavaScript. This question assesses your awareness of the tools and technologies available for developing on the Apple TV platform.

How to answer:

Explain that TVMLKit provides the bridge between JavaScript, TVML markup, and native tvOS applications. Mention that it allows for declarative UI development on Apple TV apps, similar to how HTML and JavaScript are used on the web.

Example answer:

"TVMLKit is a framework that allows you to build Apple TV apps using TVML, which is a markup language similar to HTML, and JavaScript. It provides the bridge between your JavaScript code, the TVML markup, and the native tvOS application. This allows for declarative UI development, making it easier to create user interfaces for Apple TV apps. It's kind of like how you would use HTML and JavaScript to build a website, but for tvOS."

## 25. How do you handle memory leaks in Swift?

Why you might get asked this:

Memory leaks can cause performance issues and app crashes. This question assesses your ability to identify and prevent memory leaks in Swift code.

How to answer:

Explain that memory leaks often occur through strong reference cycles. Describe how to fix them by using weak or unowned references to break the cycles between instances. Provide an example of a common scenario where a strong reference cycle can occur, such as with closures or delegates.

Example answer:

"Memory leaks often happen because of strong reference cycles, where two or more objects hold strong references to each other, preventing ARC from deallocating them. The way to handle this is to use weak or unowned references to break those cycles. For example, if you have a delegate relationship where the delegate holds a strong reference to the delegating object, you can make the delegate reference weak. This way, when the delegating object is deallocated, the delegate reference automatically becomes nil, breaking the cycle. Using Verve AI during your interview preparations can increase the chances of knowing the best answer and delivery for this question."

## 26. What is the difference between weak and unowned references?

Why you might get asked this:

weak and unowned references are used to break strong reference cycles and prevent memory leaks. This question assesses your understanding of the nuances between these two types of references.

How to answer:

Explain that weak references are optional and automatically become nil when the referenced object is deallocated. In contrast, unowned references are non-optional and assume the referenced object will always exist during their lifetime. Emphasize that using unowned references can lead to crashes if the referenced object is deallocated.

Example answer:

"weak and unowned references are both ways to avoid strong reference cycles, but they're used in slightly different scenarios. A weak reference is optional and automatically becomes nil when the object it references is deallocated. An unowned reference, on the other hand, is non-optional and assumes that the object it references will always exist and not be deallocated while it’s in use. If you try to access an unowned reference after the object has been deallocated, your app will crash. So, you use weak when the referenced object might be deallocated, and you use unowned when you're certain that the referenced object will outlive the reference."

## 27. What is the difference between frame and bounds in UIKit?

Why you might get asked this:

Understanding the coordinate systems of views is essential for laying out UIs correctly in UIKit. This question assesses your knowledge of the difference between frame and bounds.

How to answer:

Explain that frame is the view’s location and size in the coordinate system of its superview, while bounds is the view’s location and size in its own coordinate system. Emphasize that frame is relative to the superview, while bounds is relative to the view itself.

Example answer:

"frame and bounds both define the size and position of a view, but they do so in different coordinate systems. The frame is the view's rectangle relative to its superview's coordinate system. The bounds is the view's rectangle relative to its own coordinate system. So, the frame tells you where the view is located within its superview, while the bounds tells you about the view's internal coordinate system. For example, if a view is rotated, its frame will change, but its bounds will stay the same."

## 28. What is the significance of @objc in Swift?

Why you might get asked this:

The @objc attribute is used to expose Swift code to the Objective-C runtime. This question assesses your understanding of how to interoperate between Swift and Objective-C code.

How to answer:

Explain that @objc exposes Swift code to the Objective-C runtime, allowing interaction with Objective-C APIs and enabling features like selectors and KVO. Mention that it's often used when working with older Objective-C codebases or when using features that rely on the Objective-C runtime.

Example answer:

"The @objc attribute is used to make Swift code available to the Objective-C runtime. This is important for interoperability with Objective-C APIs and frameworks, and it enables features like selectors, Key-Value Observing (KVO), and other dynamic capabilities that rely on the Objective-C runtime. Basically, it tells the compiler to create metadata that the Objective-C runtime can understand, allowing Swift code to be used in Objective-C contexts."

## 29. How do UI elements work in iOS?

Why you might get asked this:

UI elements are the building blocks of iOS user interfaces. This question assesses your understanding of how UI elements are structured and how they respond to user interactions.

How to answer:

Explain that UI elements refer to components visible to the user such as buttons, labels, images, and text fields. Describe how they respond to user interactions and display content on the screen. Mention that UI elements are managed by view controllers and arranged in a view hierarchy.

Example answer:

"UI elements are the visual components that make up the user interface in iOS apps, like buttons, labels, images, and text fields. They're what the user interacts with and what displays content on the screen. These elements respond to user interactions like taps, swipes, and keyboard input. Each UI element is typically managed by a view controller, and they're arranged in a hierarchical structure within the view. So, everything you see and interact with in an iOS app is made up of these UI elements."

## 30. Who calls the main app function during the app launch cycle?

Why you might get asked this:

Understanding the app launch cycle is important for understanding how iOS apps are initialized. This question assesses your knowledge of the very first steps that occur when an app is launched.

How to answer:

Explain that the main thread of the application calls the main app function, setting up the app environment before loading the initial interface. Mention that this is the entry point for the app and is responsible for initializing the app's state.

Example answer:

"The main thread of the application calls the main app function during the app launch cycle. This function is the entry point for the app and is responsible for setting up the app's environment before loading the initial interface. It’s where the app gets its initial kick-start and prepares to display the first screen to the user."

Other tips to prepare for a swift interview questions

To ace your swift interview questions, consider these strategies:

• Practice with Mock Interviews: Simulate the interview experience to get comfortable answering questions under pressure. Use tools like Verve AI to practice with an AI recruiter.

• Review Fundamentals: Ensure a solid grasp of Swift's core concepts like optionals, closures, and memory management.

• Explore SwiftUI and UIKit: Be familiar with both Apple's UI frameworks, understanding their strengths and weaknesses.

• **Study Common Algorithms and Data