Swift Developer Interview Questions

Looking for a Swift Developer to join your team? Revelo can help you source and vet top-tier candidates.

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 Interview questions

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Building a top-tier software engineering team requires more than just hiring developers with talent. It demands the right blend of technical proficiency, creativity, and interpersonal skills. The interview process should not solely focus on verifying hard tech skills. In addition to coding skills, it's important to appraise soft skills and personality traits to help ensure that a new hire will fit seamlessly into the team's dynamic and contribute innovative solutions. 

This is especially true when hiring Swift developers—professionals who can potentially operate from anywhere on the globe thanks to the increasing acceptance of remote work and diverse talent pools. Revelo provides an efficient way to connect with prime tech talent across Latin America who are ready to integrate into any team as full-time hires. 

This article defines the characteristics of a Swift developer along with targeted Swift interview questions and answers for entry-level to senior roles. These questions and insights will equip you to assess which candidates are the right fit for your organization. 

What Is a Swift Developer?

A Swift developer, sometimes called an iOS developer, is a software engineer specializing in Swift, Apple's powerful and user-friendly and object-oriented programming language for applications supported by iOS, macOS, watchOS, and tvOS app development. Companies often task these developers with creating and implementing robust applications for Apple's ecosystem—a space that continues to evolve and offer exciting opportunities for innovation.

Hiring a Swift developer makes strategic sense if a business aims to expand or strengthen its presence within the vast Apple developer and user base. Expertise in the Swift programming language means a developer can ensure smooth performance, high security standards, and seamless user experiences across all iOS devices — crucial factors for success in today's competitive app marketplace.

Entry-Level Swift Developer Interview Questions

When interviewing for an entry-level Swift developer role, assess the candidate's foundational knowledge of Swift and related Apple technologies. For entry-level candidates, don’t expect a massive portfolio of projects outside of an academic setting. At this stage, the focus should be on gauging their grasp of standard coding practices, problem-solving abilities, and familiarity with typical app development cycles. These questions can provide useful insights into their technical competence and potential for growth. Here are some questions to ask when interviewing for an entry-level Swift developer position.

Can you explain the difference between "struct" and "class" in Swift?

This question evaluates the candidate's grasp of core Swift concepts. A well-rounded response should highlight that both are used to define properties and methods: Struct is a value type while class is a reference type. The candidate's ability to discuss scenarios for using each can show their practical understanding of the language.

Can you describe how you would handle errors in Swift coding?

This question probes the candidate's problem-solving skills. The answer should include mention of techniques like try-catch statements, error propagation, optional types, and assertions.

Can you explain what ARC is and how it works in Swift?

Automatic Reference Counting is a crucial part of memory management in iOS applications. A candidate's answer should demonstrate their understanding of this fundamental aspect of Swift programming, including how it helps to avoid memory leaks that could cause application crashes or consume unnecessary resources.

How would you explain "Optional" in Swift?

This question is designed to test their understanding of one of Swift's unique features: Optional. Their ability to explain its usage and benefits, such as preventing null reference errors and contributing to safer code, can indicate a strong grasp of the language's fundamentals.

Can you explain what closures are in Swift?

Closures are self-contained blocks of code that developers can execute together without naming a function so they can pass it around. A candidate should be able to demonstrate how they've used closures in a project and explain their benefits such as capturing and storing references to variables and constants.

Mid-Level Swift Developer Interview Questions

For a mid-level Swift developer role, you'll want to dive deeper into the candidate's knowledge and experience. Interview questions should explore their understanding of more complex concepts, their capability to optimize code performance, and how they approach collaboration in a team setting. At this level, it’s likely that Swift and iOS programmers will train and mentor new hires and junior level employees. Here are a few interview questions that can help you assess these areas for a mid-level Swift developer position.

Can you explain the role of GCD and OperationQueues in Swift?

This question assesses their knowledge of concurrency and multi-threading in Swift which are crucial for ensuring smooth user experiences. A strong response should discuss how these tools manage multiple tasks and prevent applications from freezing during intensive operations.

How would you improve the performance of a slow-running Swift application?

The ability to optimize code is a key attribute of a mid-level developer. Their answer should touch on practices like using appropriate data type and memory management techniques and reducing redundancy — all of which demonstrate their proactive approach to performance efficiency.

Can you describe a challenging team project you've worked on and how you contributed?

As a company leader, you know how important teamwork and communication are, especially as projects grow more complex. This question can reveal how they handle collaboration and problem-solving within a team context, and their ability to contribute effectively to achieving shared objectives.

Can you discuss the uses of various testing methods in Swift?

This question delves into the candidate's understanding of testing paradigms in Swift. A well-considered answer should discuss the importance of unit testing, integration testing, and UI testing. Their response can give you insights into their commitment to delivering high-quality, reliable software.

What’s your approach to managing dependencies in a Swift project?

Dependency management is a vital aspect of any software development project. An experienced developer should talk about how they handle dependencies using tools like CocoaPods or Carthage, and explain their preference and the specific scenarios in which they might choose one over the other.

Senior-Level Swift Developer Interview Questions

Expect senior-level Swift developers to guide teams and make critical decisions that affect the overall project outcome. Technical Swift concepts for developers at this level should be easily explained, though it’s not likely that senior-level programmers will be executing lower-level code on a daily basis. So, when interviewing for this role, shift the questions toward strategic thinking, architectural knowledge, and leadership abilities. Here are some questions that can help you gauge a senior-level Swift developer's capabilities.

Can you explain how you would design an efficient data persistence layer in Swift?

This question probes the candidate's architectural acumen and their ability to design scalable and efficient solutions in Swift. An insightful reply includes discussions around CoreData or SQLite, touching on critical factors like data security, performance optimization, and accessibility. Their response can reveal their proficiency in crafting sustainable designs that serve both current needs and future scalability.

How do you approach making architectural decisions when working on a new project?

The intent of this question is to uncover the candidate's strategic thinking prowess and familiarity with various architectural patterns such as MVC or MVVM. A thoughtful answer should reveal how they balance immediate project requirements with long-term considerations such as scalability, maintainability, and potential integration of future technologies. This answer can help you gauge their ability to foresee potential challenges and build systems that are flexible enough to evolve over time.

Can you describe how you approached leading a team through a challenging project phase?

This question aims to gauge the candidate's leadership style and crisis management skills. Their response can offer insights into their ability to sustain team morale under pressure, navigate conflicts, ensure transparency in communication, and deliver results despite setbacks. Their approach towards problem-solving in these scenarios can also hint at their ability to drive innovation and foster resilience within the team.

How do you stay updated with the latest developments in Swift programming and iOS development?

You expect a senior-level developer to be at the forefront of industry trends. Their answer could involve following influential developers or organizations on social media platforms, attending webinars, seminars, and conferences, or participating in online forums among other methods — indicating their commitment to continuous learning.

How would you handle transitioning an existing Objective-C app to Swift?

This question is particularly pertinent given the ongoing industry shift towards Swift. It explores not only their proficiency with both languages but also their strategic approach to significant codebase transitions. A comprehensive answer should refer to incremental migration, interoperability of Swift and Objective-C, testing at every stage, and effectively communicating the transition plan to all stakeholders. Their response will shed light on their ability to manage complex tasks while minimizing disruption.

Hire Swift Developers With Revelo

Sourcing, vetting, and hiring top-notch Swift developers can be a daunting task. That's where Revelo comes in — we match you with highly qualified Swift developers from our platform. Our talent pool consists of rigorously vetted professionals who are time-zone-aligned and proficient in English, ensuring seamless integration into your team. Plus, we handle payroll, benefits administration, taxes, and local compliance adherence. Contact us to hire the top Swift developers for your upcoming software development projects.

Why Choose Revelo?

Quick turnaround for candidate shortlists

A vast talent pool of 
pre-vetted developers

Professional sourcing, vetting, and onboarding support

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Miguel F.
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EXPERIENCE
7 years
AVAILABILITY
Full-time
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