Uplift iOS Interview
The Guide is for YOU if
- You are preparing for an iOS interview and want to improve your skills and knowledge and looking to level up your interview game and land your dream job.
- You want to gain confidence and ease during iOS interviews by learning expert tips and curated strategies.
- You want access to a comprehensive list of iOS interview QA to practice and prepare.
While the basic technical questions are important, many interviewers also like to ask more open-ended and creative questions to gauge your problem-solving skills, your design sense, and your overall knowledge of the iOS ecosystem.
Here are some examples of topics that you may encounter in an iOS interview which should be tackled first:
- Swift language features: While you should already be familiar with the basics of Swift, you may be asked about advanced features such as protocol-oriented programming, functional programming, or type inference. You may also be asked about the differences between Swift and other languages, or about the trade-offs of using Swift versus Objective-C.
- iOS frameworks and APIs: As an iOS developer, you should be familiar with the most important frameworks and APIs that are available on the platform. You may be asked about specific frameworks, such as UIKit, Foundation, or Core Graphics, or about APIs that are used for common tasks, such as networking, data persistence, or animation. You should be able to explain the purpose and usage of these frameworks and APIs, as well as their pros and cons.
- App architecture and design patterns: As an iOS developer, you should be able to design and implement an app that is scalable, maintainable, and testable. You may be asked about design patterns and architectures that you have used in the past, such as MVC, MVVM, or VIPER, and how you applied them to solve specific problems. You should be able to explain the benefits and drawbacks of different architectures and patterns, and how you choose the appropriate one for a given project.
- User experience and interface design: While technical skills are important, an iOS developer should also be able to create an app that is intuitive, user-friendly, and visually appealing. You may be asked about your design philosophy, your approach to user research and usability testing, or your favorite iOS apps and why you like them. You should be able to demonstrate your design skills by discussing your portfolio or by sketching out ideas on a whiteboard.
As iOS developers, we mostly invest our time in Xcode to implement and build iOS projects. We also use some common iOS development tools, frameworks, dependency managers, and build infrastructures. In this article, I will add a few bonus questions that are asked in the iOS interview which are mostly related to tools and not related to programming language.
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What is a view debugger in Xcode? Why view debugger is important?
The view debugger in Xcode is a tool that allows you to debug and inspect the layout and hierarchy of views in your app. It helps you understand how your app is rendering its user interface and identify issues such as layout constraints, overlapping views, or performance problems.
The view debugger is important because it allows you to see how your app looks and behaves at runtime, and helps you find and fix issues that may not be apparent when you build and run your app in Xcode. It also provides tools for inspecting the properties and attributes of views, including the constraints, frames, and transforms applied to them.
To use the view debugger in Xcode, you can follow these steps:
- Build and run your app in the simulator or on a device.
- In the Xcode toolbar, click the “Debug View Hierarchy” button or choose “Debug View Hierarchy” from the “View” menu.
- The view debugger window will appear, showing the hierarchy of views in your app and their attributes.
- You can use the tools in the view debugger window to inspect and debug your views, such as the “Inspector” panel to view and edit the attributes of a view, or the “Debug Options” panel to enable or disable debugging features.
- You can also use the “Pause on Issues” button to pause the execution of your app when an issue is detected, or use the “Step Over”, “Step Into”, and “Step Out” buttons to control the execution flow.
By using the view debugger in Xcode, you can improve the quality and performance of your app, and ensure that it is rendering correctly on different devices and platforms.
What is the use case of Symbolic breakpoint in Xcode?
A symbolic breakpoint in Xcode is a type of breakpoint that is set based on a symbol, such as a function name or a method name, rather than a specific line of code. It allows you to pause the execution of your app at a specific point in the code, based on a condition that you specify.
Symbolic breakpoints are useful in a variety of scenarios, such as:
- Debugging specific functions or methods: You can set a symbolic breakpoint on a function or method name, and the debugger will pause the execution whenever that function or method is called. This can be helpful when you want to inspect the arguments and return values of the function, or when you want to debug a specific part of your code.
- Debugging third-party libraries or frameworks: You can set a symbolic breakpoint on a symbol that is defined in a third-party library or framework, and the debugger will pause the execution whenever that symbol is used. This can be helpful when you want to understand how a library or framework is used in your code, or when you want to debug an issue that involves a library or framework.
- Debugging system APIs or libraries: You can set a symbolic breakpoint on a symbol that is defined in a system API or library, and the debugger will pause the execution whenever that symbol is used. This can be helpful when you want to understand how a system API or library is used in your code, or when you want to debug an issue that involves a system API or library.
To set a symbolic breakpoint in Xcode, you can follow these steps:
- In the Xcode toolbar, click the “Add Breakpoint” button or choose “Add Breakpoint” from the “Debug” menu.
- In the “Add Breakpoint” dialog, select the “Symbolic Breakpoint” tab.
- Enter the symbol name in the “Symbol” field, and optionally specify the module and file name if necessary.
- Click “Add” to create the symbolic breakpoint.
By using symbolic breakpoints in Xcode, you can quickly and easily debug specific parts of your code and identify issues that may not be apparent when you build and run your app in Xcode.
What are the key challenges in creating accessible apps?
There are several main problems that need to be addressed when making apps accessible:
- Visually impaired users need larger text sizes, high-contrast color schemes, and alternative text for images.
- Hearing impaired users need closed captions and subtitles for videos, and visual cues for audio events.
- Motor impaired users need larger touch targets and the ability to navigate the app using voice commands or a switch device.
- Cognitively impaired users need simple, easy-to-understand language and minimal distractions.
What measures are typically implemented in apps to improve accessibility?
To make apps more accessible, developers can implement the following accommodations:
- Provide adjustable text sizes and high-contrast color schemes.
- Include alternative text for images, closed captions, and subtitles for videos.
- Allow users to navigate the app using voice commands or a switch device.
- Use simple, easy-to-understand language and minimal distractions.
- Provide a setting for the users to adjust the font size and contrast.
- Provide the option for users to navigate using a keyboard.
- Provide a clear and consistent layout throughout the app.
- Provide a clear indication of the currently selected element.
- Provide a clear visual indication of the progress of a task or process.
- Provide clear feedback when buttons are pressed or other actions are taken.
What is the difference between build settings, build phases and build rules in Xcode?
In Xcode, build settings, build phases, and build rules are different components that are used to configure and control the build process of your app. Here is a brief overview of each component:
- Build settings: Build settings are the variables and values that are used to configure the build process of your app. Build settings can include options such as the target platform, the deployment target, the build configuration, the optimization level, the warning and error messages, and the preprocessor macros. Build settings can be global, meaning they apply to all targets and configurations in your project, or they can be specific to a target or a configuration.
- Build phases: Build phases are the steps in the build process that are used to compile and link your source code, resources, and frameworks. Build phases can include tasks such as compiling source code files, copying resources, linking libraries, and creating the final product (e.g., an app bundle or a framework). Build phases are specified in the “Build Phases” tab of the target editor in Xcode, and they are executed in the order that they are listed.
- Build rules: Build rules are the instructions that are used to specify how Xcode should process certain types of files during the build process. Build rules can include options such as the input and output files, the build settings, and the script commands that are used to transform or generate the files. Build rules are specified in the “Build Rules” tab of the target editor in Xcode, and they are used to customize the build process for specific types of files, such as custom file formats or preprocessed files.
By configuring build settings, build phases, and build rules in Xcode, you can customize and optimize the build process of your app to meet your specific requirements and constraints.
What is the capability in a Xcode Project?
In Xcode, a capability is a feature or resource that your app can use or access. Capabilities are defined in the “Signing & Capabilities” tab of the project editor in Xcode, and they are used to enable or disable specific features or resources for your app.
There are many different types of capabilities that you can enable or disable for your app in Xcode, depending on your requirements and constraints. Some examples of capabilities include:
- App Groups: This capability allows your app to share data and resources with other apps that are in the same app group.
- Associated Domains: This capability allows your app to use app-specific URLs to open other apps, or to handle incoming URLs from other apps.
- iCloud: This capability allows your app to access iCloud services, such as the iCloud key-value store, the iCloud document store, or the iCloud Core Data store.
- In-App Purchase: This capability allows your app to sell or offer digital content or services to users.
- Game Center: This capability allows your app to use the Game Center service to manage leaderboards, achievements, and multiplayer games.
- HealthKit: This capability allows your app to access and store health data from the Health app or from third-party health apps.
- HomeKit: This capability allows your app to control and communicate with home automation accessories, such as lights, thermostats, or security systems.
- Push Notifications: This capability allows your app to receive push notifications from a server or from other apps.
- Siri: This capability allows your app to integrate with Siri, the voice-activated assistant, and provide voice commands or responses.
By enabling or disabling capabilities in your Xcode project, you can customize the features and resources that your app can use or access. You should carefully consider which capabilities you need for your app, and only enable the ones that are required. Enabling unnecessary capabilities can increase the size and complexity of your app, and may also require you to implement additional code or resources to handle them.
What are the most common CI/CDs for a large-scale iOS app?
Continuous integration/continuous delivery (CI/CD) is a software development practice that involves integrating and testing code changes frequently, and automatically deploying them to production or staging environments. CI/CD helps teams to deliver software faster, more reliably, and with fewer errors, by automating the build, test, and release processes.
There are many different CI/CD tools and platforms that can be used for large-scale iOS apps, depending on your specific requirements and constraints. Here are some examples of popular CI/CD tools that are commonly used for iOS development:
- Fastlane: Fastlane is an open-source tool that helps iOS and Android developers to automate the build, test, and release processes of their apps. Fastlane is easy to use, customizable, and extensible, and it integrates with many different tools and services, such as Xcode, Git, Jenkins, and Crashlytics.
- Jenkins: Jenkins is a popular open-source automation server that can be used to automate the build, test, and release processes of iOS apps, as well as other types of software. Jenkins is highly configurable, and it can be integrated with many different tools and services, such as Git, Fastlane, and Xcode.
- CircleCI: CircleCI is a cloud-based CI/CD platform that is designed for modern software development teams. CircleCI supports iOS and other mobile platforms, and it offers a range of features and integrations that are designed to improve the speed, reliability, and security of the build, test, and release processes.
- Bitrise: Bitrise is a cloud-based CI/CD platform that is specifically designed for mobile app development. Bitrise supports iOS, Android, and other mobile platforms, and it offers a range of features and integrations that are designed to help teams automate the build, test, and release processes of their apps.
By using a CI/CD tool or platform, you can streamline and optimize the build, test, and release processes of your large-scale iOS app, and deliver updates and features to your users faster and more reliably.
How has Swift changed since it was first released in 2014?
Since its initial release in 2014, Swift has undergone several updates and improvements. Some of the key changes include:
- Swift 2 introduced error handling using try-catch statements and introduced new features such as protocol extensions and availability checking.
- Swift 3 introduced a new naming convention for functions and variables, a new Swift Package Manager for managing dependencies, and improved performance.
- Swift 4 introduced a new encoding and decoding model for working with JSON, improved support for working with strings and collections, and introduced new features such as the Codable protocol.
- Swift 5 introduced binary compatibility, which allows apps to be more stable and efficient when they run on different versions of Swift.
- Swift 5.3 introduced new features such as Property Wrappers, Opaque Result Types and Result Builder, Multi-pattern catch clauses, and more.
- Swift 5.3 also includes improvements to the standard library and language, making it more expressive, more efficient, and more stable.
Code analyzer in iOS
Code analyzers are tools that automatically analyze source code and identify potential issues or problems, such as bugs, vulnerabilities, performance issues, or style violations. Code analyzers can be used to improve the quality, security, and maintainability of an iOS app, by identifying and fixing problems before they are deployed to users.
There are many different code analyzers that are available for iOS development, and they can be classified into two main categories: static code analyzers and dynamic code analyzers.
- Static code analyzers: Static code analyzers are tools that analyze source code without executing it. Static code analyzers can be run at any time, and they can identify a wide range of issues, such as syntax errors, style violations, type errors, nullability issues, and security vulnerabilities. Some examples of static code analyzers for iOS development are Clang Static Analyzer, SwiftLint, and OCLint.
- Dynamic code analyzers: Dynamic code analyzers are tools that analyze source code while it is being executed. Dynamic code analyzers can identify issues that are related to runtime behavior, such as memory leaks, performance bottlenecks, and threading issues. Some examples of dynamic code analyzers for iOS development are Instruments, Shark, and Xcode Memory Graph Debugger.
By using code analyzers, you can improve the quality, security, and maintainability of your iOS app, and catch problems early in the development process, before they are deployed to users. Code analyzers can also help you to enforce coding standards, and to improve the overall design and structure of your app.
How could you test a low network in Simulator?
Testing an iOS app on the Simulator with low network conditions can be useful to ensure that the app handles network failures and slowdowns gracefully, and provides a good user experience even under adverse conditions.
To test low network conditions in the Simulator, you can use the Network Link Conditioner, which is a tool that is available on macOS. The Network Link Conditioner allows you to simulate various network conditions, such as low bandwidth, high latency, or packet loss, and to see how your app behaves under these conditions.
To use the Network Link Conditioner in the Simulator, follow these steps:
- Open System Preferences on your Mac, and go to the Network panel.
- In the Network panel, click the Action menu (gear icon), and choose “Open Network Link Conditioner”.
- In the Network Link Conditioner window, select the “Profiles” tab.
- Click the “+” button to create a new profile.
- In the “Profile Name” field, enter a name for the profile.
- In the “Profile Settings” section, choose the network conditions that you want to simulate. For example, you can choose a low bandwidth or a high latency, or both.
- Click “Apply” to apply the profile.
- In the Simulator, open the app that you want to test, and use it as you normally would.
- To stop using the Network Link Conditioner, go back to the Network Link Conditioner window, and click “Stop”.
By using the Network Link Conditioner, you can test how your app behaves under low network conditions, and make sure that it provides a good user experience even when the network is slow or unreliable.
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.
If you are interested in 5 parts Swift Series –
✍️ Written by Ishtiak Ahmed
Get Ready to Shine: Mastering the iOS Interview
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