13 Swift Interview Questions & Answers to Get Hired Instantly


Interested in switching to a coder’s career? Choosing to become a Swift developer is one of your great decisions. The language is highly-competitive, allowing you to create mobile and desktop apps and scale up to cloud services.

You might see some predictions on fluctuating demand for Swift professionals, depending on changes in Apple’s operating system and the coding industry in general. However, the key benefit of Swift is that it’s mainly used for iOS development, a feature that makes it an almost ever-green demanded skill.

So, if you’re on the path of becoming a Swift developer, there are two key things you should do:

  • as obvious as it might sound, learn Swift
  • further, find a company that will employ you as a beginner and allows you to test your skills on real projects. 

Let’s break your further actions down. 

Where to learn Swift?

At WildLearner, you can learn Swift for absolutely free, with 57 interactive online lessons. You will get rich learning material combined with testing quizzes and coding assignments. Further, you can get a free certificate, which will help you get additional credits when applying for a Swift developer’s role. 

How to prepare for Swift interview questions?

Let’s not pretend we can accurately predict the questions an HR manager will ask you during your next interview. However, we can provide you with a list of the most frequently asked Swift interview questions that you are very likely to answer regardless of the company you apply. We’ll also provide you with short & sweet answers to those questions so that you don’t think long and impress an interviewer with deep knowledge of Swift.

Question 1: What is a Swiftlint?

Answer: Swiftlint is a tool that helps different programmers to enforce the same style and conventions. The best thing about Swiftlint? It’s open-source, accessible, and actively maintained.

Question 2: What can you do with iOS device simulators?

Answer: Swift developers use iOS device simulators to test their Swift apps on various devices. Default iOS simulator enables users to test Swift applications in different screen sizes and resolutions and run Swift code on a variety of Apple devices.

Question 3: What is a Swift protocol?

Answer: Swift protocols are blueprints of methods and properties, which Swift developers use to declare the functionality they want their classes or structures to provide. A swift protocol has a syntax similar to a class.

Question 4: What is a Guard statement in Swift?

Answer: Swift developers use the Guard statement to transfer program control out of scope if one or more conditions are not met. Swift guard is similar to Swift if statement, with the difference that Swift guard can be used only on boolean conditionals, and it must have an else clause.

Question 5: How to use PLIST in Swift?

Answer: PLIST is used to store Swift data with a .plist data extension. The advantage of Swift PLIST is that it allows you to create a Swift collection, which can be used in any place where there is a need for an Array or a literal dictionary.

Question 6: Explain the Swift dictionary

Answer: Swift dictionary is a collection of key-value pairs, where the Swift dictionary keys are always unique. This means each value connects to a unique key. Swift dictionaries can be created using Swift literal syntax or the Dictionary type alias.

Question 7: Which are the three primary collection types in Swift?

Answer: Swift has three main collection types: Swift array, Swift set, and Swift dictionary. They are used to store Swift data. Swift arrays are ordered collections and Swift dictionaries have keys to access each value stored in a Swift dictionary.

Question 8: What’s different between Array and NSArray?

Answer: NSArray can hold more types of data than Array, which can store only one type of data. Besides, NSArray is an immutable reference type, whereas Array belongs to the value type.

Question 9: How are Swift classes different from Swift structure?

Answer: Swift class is a reference type; the Swift structure is a value type. Swift classes are created with the keyword class, whereas structures are built with struct. On top of that, structures can be copied, while classes do not have this feature.

Question 10: How to append arrays in Swift?

Answer: Swift arrays can be appended using the append() method. Other than that, a developer can append arrays with + or += methods. Swift arrays are always mutable.

Question 11: What does a “mutating” keyword do in Swift?

Answer: Swift developers use the “mutating” keyword to change Swift structure values internally. Swift structures are immutable by default, but the Swift mutating keyword allows you to modify Swift properties and methods of classes and structures.

Question 12: How to deal with runtime errors in Swift?

Answer: Swift runtime error is a special kind of exception that occurs when your app runs. So, usually, in such cases, developers work on Swift conditions that may cause their apps to crash or behave unexpectedly.

Question 13: What is optional chaining?

Answer: Swift developers use Swift optional chaining to call properties, methods, or subscripts on an optional value and check if those calls will succeed. Swift optional chaining is a process for calling these values of Swift that might currently be nil.

To sum up

The above list contains some essential Swift interview questions and answers, which will help you during your interview. However, as mentioned before, this is not the whole list of questions you can be asked. So, keep in mind that you should be prepared to answer any question related to Swift development.

Good luck! And don’t forget to keep practicing! 🙂