Welcome to our comprehensive iOS Interview Guide for UIKit & SwiftUI! Whether you’re a seasoned developer or just starting out, this guide will help you ace your next interview. We’ve compiled a list of the top 30 questions you’re likely to encounter in a iOS interview, covering everything from UIKit and SwiftUI. With clear explanations and sample answers, this guide will give you the confidence you need to impress your interviewer and land your dream job. So if you’re looking to up your iOS game in 2023, this guide is for you!

Can you explain the purpose of UIMenuController in iOS development?

UIMenuController is a class in iOS that is used to display a menu of options to the user. It is typically used in conjunction with a UITextView or UITextField to provide options such as copy, paste, and select all.

Can you tell me the difference between a UIImage and a UIImageView in iOS development?

A UIImage represents an image that can be displayed in an iOS app, while a UIImageView is a UI element that can display an image. UIImageView can be used to display animations, images, and other content.

Can you explain the difference between aspect fill and aspect fit when displaying an image in iOS development?

Aspect fill and aspect fit are two different ways to display an image in an iOS app. Aspect fill will scale the image to fill the entire space, potentially cropping parts of the image. Aspect fit will scale the image to fit the entire space, potentially leaving some empty space.

Can you explain the purpose of anchors in Auto Layout in iOS development?

Anchors in Auto Layout are used to specify the position and size of a view relative to its parent view or other layout guides. This makes it easy to create responsive user interfaces that adapt to different screen sizes and orientations.

Can you give me a breakdown of the pros and cons of using viewWithTag() in iOS development?

The viewWithTag() method in iOS is used to retrieve a view from the view hierarchy by its tag property. Pros of using this method include the ability to quickly retrieve views, even if they are deeply nested in the view hierarchy. Cons include the potential for naming collisions if multiple views have the same tag and the potential for bugs if a view’s tag is changed but the code that references it is not updated.

Can you tell me about the purpose of reuse identifiers for table view cells in iOS development?

Reuse identifiers for table view cells are used to improve performance in iOS apps. When a table view needs to display a large number of cells, it will dequeue cells that have already been created but are no longer visible, instead of creating new ones. This can significantly improve the performance of the app.

Can you explain to me, as a Junior iOS developer, what UIKit segues are and how they work?

UIKit segues are used to transition between different parts of an iOS app’s user interface. They allow developers to specify the transition animation and prepare any data that needs to be passed between the two views. Segues are typically triggered by user interaction, such as tapping a button, and can be configured in the storyboard.

Can you tell me how a view’s intrinsic content size aids in Auto Layout in iOS development?

A view’s intrinsic content size helps Auto Layout determine the appropriate size for a view based on its contents. This allows for dynamic layout adjustments as the content changes.

Can you explain to me the purpose of storyboard identifiers in iOS development?

Storyboard identifiers are used to identify specific views or view controllers in a storyboard, allowing them to be easily accessed and instantiated in code.

Can you tell me the purpose of UIActivityViewController in iOS development?

UIActivityViewController is used to present a standard view for sharing content, such as text or images, with other apps or services.

When would you choose to use a collection view rather than a table view in iOS development?

A collection view is typically used when displaying a large number of items that are organized into multiple sections, or when displaying items with a more complex layout than a table view can support.

Can you explain the difference between @IBOutlet and @IBAction in iOS development?

@IBOutlet is used to create a reference to a user interface element, such as a label or button, in order to manipulate its properties in code. @IBAction is used to create an action method, which is a method that will be called in response to an event, such as a button tap.

Can you tell me about the benefits of using child view controllers in iOS development?

Child view controllers allow for better organization and reuse of code in a larger application. They also allow for better management of memory, as a child view controller can be removed from memory when it is no longer needed.

Can you tell me how XIBs differ from storyboards in iOS development?

XIBs (short for “NIB,” or “NeXT Interface Builder”) are XML-based files that are used to create individual user interface elements, such as a custom table cell. Storyboards, on the other hand, are used to create the overall layout and flow of an application’s user interface. XIBs allow for more fine-grained control over individual elements, while storyboards provide a more holistic view of the interface.

Can you tell me the purpose of UIVisualEffectView in iOS development?

UIVisualEffectView is used to apply a blur or vibrancy effect to a view. It allows developers to add subtle visual effects to views without having to create custom drawing code.

Can you tell me about the purpose of IBDesignable in iOS development?

IBDesignable is a keyword that can be added to a UIView subclass to indicate that it can be rendered directly within Interface Builder, allowing for faster iteration during the design and layout of the User Interface.

What is implicit stacking?

Implicit stacking in SwiftUI

What are the different layout options available in SwiftUI and when should you use each one?

There are several layout options available in SwiftUI, including VStack, HStack, ZStack, List, and Form. You should use VStack and HStack for vertical and horizontal layouts, respectively, ZStack for overlaying views, List for creating a scrolling list of items, and Form for creating a form-like layout.

When should you consider SwiftUI over UIKit for your next project?

SwiftUI vs UIKit – Benefits and Drawbacks of SwiftUI

How do you respond to user interactions in SwiftUI?

You can use the onTapGesture() modifier to respond to tap gestures, and the onLongPressGesture() modifier to respond to long press gestures. You can also use the .onReceive() method to respond to external events, such as notifications or changes in the environment.

How do you integrate SwiftUI views into a UIKit project? / How does SwiftUI relate/correlate with storyboards?

You can use the UIHostingController class to wrap a SwiftUI view and present it in a UIKit app. You can also use the UIViewRepresentable protocol to create a wrapper for a UIKit view that can be used in a SwiftUI app.

Which frameworks do you like most apart from UIKit?

iOS interview Prep 2023: Mastering Frameworks

Could you explain the concept of SwiftUI’s environment to a Junior developer, including its purpose and usage?

allows views to access shared data or global settings without having to pass them down through multiple views as props. The environment can be set on a parent view and its child views can access it using the Environment object. This can be useful for things like setting a theme, providing localization information, or passing down a managed object context.

Can you explain the purpose and usage of the @State property wrapper in SwiftUI?

The @State property wrapper is used in SwiftUI to create a state variable that can be changed by the view. When the value of a state variable changes, the view will automatically be re-rendered with the new value. State variables are only accessible from within the view that owns them, and their changes do not trigger updates in any other views.

Can you elaborate on the difference between a view’s initializer and the onAppear() method in SwiftUI?

The view’s initializer is used to set up the initial state of a view when it’s first created. On the other hand, the onAppear() method is called every time the view appears on the screen, whether it’s the first time or not. It’s useful to perform actions that need to be done every time the view appears, such as fetching data or starting animations.

Can you provide information on the functionality of the @Published property wrapper in SwiftUI?

The @Published property wrapper is used to automatically notify SwiftUI views when a property on an object changes. When a property marked with @Published is changed, any views that are observing it will automatically be updated. This is useful for creating data-driven views that automatically update when the data changes.

Can you provide insight on when it would be appropriate to use @StateObject versus @ObservedObject in SwiftUI?

@StateObject is used for creating a state object that is shared between multiple views. This is useful for creating a single source of truth for a piece of data that is used by multiple views. On the other hand, @ObservedObject is used to reference an object that is not owned by the view, and is typically used with a view model object.

Could you explain the mechanism for an observable object to announce changes to SwiftUI, and the corresponding methods used for this purpose?

To announce changes to SwiftUI, an observable object should use the objectWillChange publisher and call its send() method whenever it changes. Any views that are observing this object will automatically be updated when the send() method is called.

Can you provide examples of when it would be appropriate to use GeometryReader in a SwiftUI application?

GeometryReader is a view in SwiftUI that allows you to access information about the size and position of its parent view. It’s useful for creating views that are dependent on the size of their parent, such as views that need to fill up a certain percentage of the screen.

Can you explain the purpose of the ButtonStyle protocol in SwiftUI and provide examples of its usage?

The ButtonStyle protocol in SwiftUI is used to customize the appearance and behavior of a button. It allows you to define a custom view for a button, and also lets you customize the button’s animation when it’s pressed.

Could you explain the reasoning behind the use of structs for views in SwiftUI, as opposed to other options such as classes?

SwiftUI uses structs for views because structs are value types, which means that they are copied when passed around. This makes it easy to create views that are isolated from one another, making it easy to reason about the state of the app. Additionally, structs are lightweight and efficient, which is beneficial for creating views in a performance-critical environment such as iOS.

Can you provide guidance on how to implement programmatic navigation in a SwiftUI application?

In SwiftUI, programmatic navigation can be achieved by using the NavigationLink view, which allows you to navigate to a new view when a user interacts with it. You can also use the NavigationView to wrap your views and provide a navigation bar.

Fellow iOS Developers, Please Keep In Mind

• It’s important to keep in mind a few key points as you prepare for your interview. Firstly, it’s worth noting that there are over 1000 interview questions available in the interview section for you to review and prepare for. While reading the question, take the time to carefully consider your answer and think about the information that you want to convey. The answer provided here in this blog can be explained in a different way. You should also prepare your examples.
• It’s also important to remember that these interview questions are not meant to be difficult. The interviewer is not looking to challenge you, but rather to start a conversation that will allow your abilities and interests to come to the forefront. They want to get to know you and your experience better.
• Finally, it’s crucial to avoid simply answering questions with a “yes” or “no.” Interviewers are looking for more in-depth responses that include basic understanding, reasoning, explanation, and examples. So, make an effort to elaborate on your answers and provide specific, relevant information to support your response. This will demonstrate your thoughtfulness and show the interviewer that you are well-prepared for the interview.

These links are for a series of interview questions and answers related to SwiftUI and iOS development. Part 1 covers UI basics, Part 2 covers advanced UI topics, and Part 3 covers data-related concepts. The Swift iOS interview questions and answers series is also included, with 5 parts covering various topics related to iOS development. Additionally, there is a bonus section for iOS developer interview questions.

SwiftUI Interview Questions and Answers – Part 1 – UI Basics

SwiftUI Interview Questions And Answers – Part 2 – UI Advance

SwiftUI Interview Questions And Answers – Part 3 – Data

If you are interested in 5 parts Swift Series –

Swift iOS interview questions and answers

Swift iOS interview questions and answers – Part 1

Swift iOS interview questions and answers – Part 2

Swift iOS interview questions and answers – Part 3

Swift iOS interview questions and answers – Part 4

Swift iOS interview questions and answers – Part 5

and a bonus

iOS Developer – Bonus Interview Questions

✍️ Written by Ishtiak Ahmed

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Get Ready to Shine: Mastering the iOS Interview

• Ace iOS Coding Interview
• Uplift iOS Interview - A Comprehensive Guide to iOS Interview

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