Product Perfect

Swift is a powerful and intuitive programming language developed by Apple for iOS, macOS, watchOS, and tvOS app development. It is designed to work with Apple's Cocoa and Cocoa Touch frameworks and the large body of existing Objective-C code written for Apple products. Swift is easy to use and open source, so anyone with an idea can create something incredible. It's known for its simplicity and directness in coding, offering concise yet expressive syntax that produces efficient and effective results. Swift incorporates modern programming concepts such as dynamic typing, late binding, and closures, making it a popular choice for developers.

Ask the right questions secure the right Swift talent among an increasingly shrinking pool of talent.

First 20 minutes

General Swift app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in Swift application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you define Swift?

Swift is a powerful and intuitive programming language developed by Apple for iOS, macOS, watchOS, and tvOS app development. It's designed to give developers more freedom than ever before. Swift is easy to use and open source, so anyone with an idea can create something incredible.

What are the basic data types in Swift?

The basic data types in Swift are String, Int, Float, Double, Bool, Array, Dictionary, Set, Optional, and Tuple.

Describe the difference between 'let' and 'var' in Swift.

'let' is used to declare constants while 'var' is used to declare variables. Once a value is assigned to a constant using 'let', it cannot be changed. On the other hand, a variable declared using 'var' can be changed.

How would you handle optional values in Swift?

Optional values in Swift can be handled using optional binding and optional chaining. Optional binding is a method to find out whether an optional contains a value, and if so, to make that value available as a temporary constant or variable. Optional chaining is a process for querying and calling properties, methods, and subscripts on an optional that might currently be nil.

What are closures in Swift?

Closures are self-contained blocks of functionality that can be passed around and used in your code. They are similar to blocks in C and Objective-C and to lambdas in other programming languages.

The hiring guide has been successfully sent to your email address.

Oops! Something went wrong while submitting the form.

What you’re looking for early on

Has the candidate demonstrated in-depth knowledge of Swift?

Are they showing strong problem-solving skills?

Does the candidate have experience with other relevant technologies such as Objective-C or Xcode?

Is the candidate able to articulate their thoughts and explain their process clearly?

Next 20 minutes

Specific Swift development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

Describe the difference between classes and structures in Swift.

Both classes and structures can have properties and methods, but there are some differences. Classes are reference types and they support inheritance, which means you can create a class that inherits properties and methods from another class. Structures are value types and do not support inheritance.

How would you use the 'guard' statement in Swift?

The 'guard' statement is used to transfer program control out of a scope if one or more conditions aren’t met. It's typically used to early exit from a function, loop, or condition if certain requirements aren't fulfilled.

What are generics in Swift?

Generics are one of the most powerful features of Swift, and much of the Swift standard library is built with generic code. With generics, you can write flexible, reusable functions and types that can work with any type, subject to requirements that you define.

Describe the difference between synchronous and asynchronous tasks in Swift.

Synchronous tasks block the execution of further tasks until they're finished, while asynchronous tasks allow further tasks to continue before they're finished. Asynchronous programming is typically used in Swift to improve performance for long-running tasks such as networking requests.

How would you use the 'defer' statement in Swift?

The 'defer' statement is used to execute a set of statements just before code execution leaves the current block of code. This statement is executed regardless of how execution leaves the current block of code — whether it leaves because an error was thrown or because of a statement such as return or break.

The hiring guide has been successfully sent to your email address.

Oops! Something went wrong while submitting the form.

At this point, a skilled Swift engineer should demonstrate strong problem-solving abilities, proficiency in Swift programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Swift.

What does this Swift code do?
let greeting = "Hello, World!"
print(greeting)
This code declares a constant string with the value 'Hello, World!' and then prints that string to the console.
What will be the output of this Swift code?
var x = 5
x += 3
print(x)
This code declares a variable x with the value 5, then adds 3 to x, so the output will be 8.
What does this Swift code snippet do?
let numbers = [1, 2, 3, 4, 5]
let squaredNumbers = numbers.map { $0 * $0 }
print(squaredNumbers)
This code declares an array of numbers, then creates a new array where each number is squared. So the output will be [1, 4, 9, 16, 25].
What will be the output of this Swift code?
import Dispatch

DispatchQueue.global(qos: .background).async {
  print("This is run on the background queue")
  DispatchQueue.main.async {
    print("This is run on the main queue")
  }
}
This code prints 'This is run on the background queue' on a background thread, then prints 'This is run on the main queue' on the main thread. The exact order of the output can vary depending on the system's scheduling of the threads.

Wrap-up questions

Final candidate for Swift Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle Swift application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What are property observers in Swift?

Property observers observe and respond to changes in a property’s value. They are called every time a property’s value is set, even if the new value is the same as the property’s current value. Swift provides two kinds of property observers: 'willSet' and 'didSet'.

Describe the difference between 'strong', 'weak', and 'unowned' references in Swift.

'Strong', 'weak', and 'unowned' are used to prevent memory leaks and they're part of Swift's Automatic Reference Counting (ARC). 'Strong' creates a strong reference to the instance it refers to and it won't allow the instance to be deallocated as long as there is a strong reference to it. 'Weak' does not keep a strong hold on the instance it refers to and it does not stop ARC from disposing of the referenced instance. 'Unowned' is similar to 'weak', except that it's used when the reference will always have a value.

How would you use the 'map', 'filter', and 'reduce' functions in Swift?

'Map', 'filter', and 'reduce' are higher-order functions in Swift. 'Map' applies a function to all elements in a collection and returns the results in an array. 'Filter' returns a new array that includes elements of an existing array that pass a condition you specify. 'Reduce' combines all items in a collection to create a single new value.

Swift application related

Product Perfect's Swift development capabilities

Beyond hiring for your Swift engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Swift projects, and can engage in multiple capacities.

Swift Consultive assessments

Swift Application Conversion Assessment Swift Application Integration Assessment Swift Data & Database Integration Assessment

Custom Swift development projects

Custom Swift App Conversion Swift Custom App Development Process App UI Design for Swift Facelifts

Hiring guide for Swift Engineers

Swift Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

What you’re looking to see on the Swift engineer at this point.

Swift Consultive assessments

Custom Swift development projects