Hire the Top 3% of Freelance iOS Developers

Demand for iOS Developers Continues to Expand

When it comes to apps that run on Apple’s iOS platform, it’s not easy to hire app developers who can deliver a high-quality finished product. As of June 2024, the Apple App Store featured more than 1.9 million apps, but in 2022 alone, the App Store rejected 1.7 million apps for falling below its standards. Still, an iOS app has to succeed in measures of user satisfaction and user engagement, not just in the App Store.

In terms of mobile app market share, is iOS app development worth the challenge? Absolutely: iOS holds almost one-third of the global market share and more than two-thirds of total subscription revenue while consistently leading the US market. Regardless of location, it’s lucrative for companies with their own mobile apps to support iOS.

To prepare for hiring top iOS developers, this guide helps you navigate relevant tech trends, understand the essentials to include in iOS developer job descriptions, and effectively interview candidates who seek to contribute to your development projects.

What Attributes Distinguish Quality iOS Developers From Others?

iOS developers are often responsible for several crucial aspects of an iOS app and its life cycle. They work in dedicated teams within a development environment like the Xcode IDE to create, debug, and maintain code written in either Swift or Objective-C (to a lesser extent). They may work heavily on the front end, collaborating with UI/UX designers to create apps in accordance with Apple’s Human Interface Guidelines.

In addition, mobile developers on smaller teams may be further tasked with creating corresponding back-end services, running DevOps processes, and helping with both manual and automated QA. Mobile apps come with various challenges that make the ability to manage data on Apple ecosystem devices like iPhones, iPads, and Apple Watches very important.

Like all mobile app developers, iOS developers may be assigned to integrate common features such as push notifications, purchase flows, or location services—it all depends on business requirements. Here are a few of the most important areas an iOS developer might work on:

• Web API integration and networking: Working with REST APIs and back-end services may be a hard requirement for certain app features. Candidates may then need to be comfortable with parsing JSON or XML data, handling network error cases appropriately, and making requests using URLSession or Alamofire in Swift, or NSURLSession in Objective-C.
• Push notifications: If your project aims to get a user’s attention in real time (even when their phone is locked), you may need an iOS programmer who knows how to use the Apple Push Notification service to leverage this popular engagement technique.
• Background tasks: Your app may need to perform short tasks (e.g., refresh or fetch) or long tasks (e.g., extensive data processing) in the background. If so, you’ll need an application developer who knows how to enable these capabilities and register tasks with Apple’s background task scheduler.
• Authentication: If your app requires a login, you’ll need an iOS developer who has experience with secure frameworks like OAuth and services specific to your tech stack like Auth0 or Firebase Authentication.

Skilled developers know when a solution already exists within the built-in features of the iOS frameworks they’re using, and won’t waste resources on reinvention. They also keep themselves current regarding Apple’s App Store guidelines so their app submissions succeed rather than requiring rework.

Core Skills for iOS App Development

No software skill sets exist in a vacuum, even in the context of proprietary technologies. Regardless of the specific use case, all iOS developers should be skilled with the following tools:

Swift/Objective-C – Swift skills alone are suitable for most projects, since Swift is Apple’s preferred language for iOS development. However, if your company maintains an Objective-C code base, this skill is a must-have for your candidates. If you’re migrating to Swift, you’ll want someone with both skills.

Swift developers should know how to leverage functional programming concepts in implementing business logic, such as composing via higher-order functions and using map(), filter(), and reduce(). They should also know how to keep apps running stably using optional types, and how to optimize compilation times by avoiding heavy reliance on type inference.

An Objective-C developer’s knowledge should go beyond basic object-oriented programming concepts like classes, objects, methods, and properties, and include protocols and categories, as well as memory management best practices, such as when to use automatic reference counting and how to avoid memory leaks. They should also be skilled with Cocoa Touch, which enables developers to access iOS-specific hardware and software features like the camera, GPS, and touch screen.

Xcode – Apple’s official IDE for iOS development, Xcode, has few viable alternatives. The best iOS developer candidates should be power users of Xcode’s code editor, integrated source control, and debugger, and have mastery of Xcode’s Interface Builder—or alternatively, SwiftUI—for building user interfaces. Candidates should also know their way around Xcode’s Instruments for performance optimization; poor performance is often caused by increasing the complexity of the UI without adequately profiling and optimizing hangs.

On smaller teams where candidates might be tasked with publishing, they should be familiar with App Store Connect as well as Xcode app signing and provisioning processes; you may even require them to have their own Apple Developer account. On any size team—even one large enough to have dedicated QA staff—proficiency using Xcode’s Simulator is a requirement for the front-line testing that developers do before releasing a build.

Complementary Skills for iOS App Development

While some complementary iOS developer technical skills will depend on your project specifics, the ones worth paying attention to on an iOS developer’s résumé will often include the following:

Core Data – In the Core Data framework, Apple provides a robust way for iOS developers to model, store, and query data without needing to know the details of underlying data technologies like SQL. Core Data yields many user benefits, such as the ability to sync app data across any Apple devices sharing an iCloud account. Knowing the standard way to do this using Core Data allows developers to spend less time reinventing a sync solution, and provides users with a sync experience that is consistent across numerous iOS apps. Most iOS development teams will be right at home with solutions done the Core Data way, so your current candidates need to be too.

Unit testing – Creating and maintaining automated tests of lower-level components (units) of your iOS codebase are a very worthwhile investment: Regression prevention, reduced QA costs, easier debugging, and a stabler codebase make unit testing a boon from both a developer and a business perspective. Meticulous developers will be in the habit of integrating unit testing with the coding and debugging workflows of their development process.

Swift Usage for iOS App Development: Hiring Swift vs. Objective-C Specialists

Swift was released in 2014 and created to be the successor to Objective-C, offering clearer and more concise syntax, faster performance, and features like automatic memory management. As a result, Objective-C has fallen out of fashion for building new apps, and is now mostly relevant in the hiring market when it comes to the maintenance and refactoring of legacy software.

Because Swift is the default choice these days, if your iOS app development project only uses Swift, the candidate pool will be a lot bigger. If you’re looking for mobile app developers to migrate a legacy Objective-C app to Swift, you’ll want to make sure they have prior experience with this process. Objective-C specialists are often proficient with Swift due to its current popularity, but Swift specialists early in their career may not have any experience with Objective-C.

How Can You Identify the Ideal iOS Developer for You?

To find your ideal iOS developer, you must first have an accurate picture of your project and its overall requirements. Start by thinking about questions like these, as applicable:

• Is it a greenfield project, a prototype, a recent launch needing scaling, or a well-established app experiencing a change in team structure?
• Does your app use any special integrations, uncommon APIs, or advanced features like real-time video processing?
• Is it written in Swift or Objective-C, and is there any plan for that to change?
• What are the strengths of your current developers and adjacent team members (designers, project managers, etc.)? What skill gaps do you need to fill?

iOS Development Common Use Cases

It’s worth considering whether your project intersects with these common use cases to ensure that candidates have the appropriate experience and specialization. The use cases for iOS development services are far-reaching and apply to nearly every industry, but broadly speaking, they most often fall into these categories:

• Apps made to generate revenue via:
  • In-app purchases, as is common with subscriptions in utility and lifestyle apps as well as mobile games.
  • Advertising, which is prevalent not only with games but also with apps that provide free services.
  • Sales of the app itself, as seen in all app categories.
• Apps built for non-revenue purposes such as:
  • Customer engagement apps that are usually provided free of charge.
  • Companion apps for specific hardware, like smart home and other IoT devices.
  • Internal apps meant only for employees, most common among larger enterprises.

Whether creating e-commerce apps, social media clients, productivity tools, home automation, mobile games, or myriad other categories of mobile apps, companies wanting their offerings to run on iPhones will need iOS developers.

After you’ve considered your particular use case, you can list the gaps in your team. Next up in the hiring process is to discover what sort of iOS developer will fill them best. It’s important to narrow your search to the specific level of experience necessary to get the job done and satisfy all project requirements.

Distinguishing Between Junior, Mid-level, and Senior iOS Developers

Often having less than two years of experience in iOS development, a junior developer can create (and perhaps publish) basic iOS applications independently, but will raise time requirements for senior team members, who will need to mentor them in best practices, advanced feature implementation, scaling, and enterprise-quality publishing standards. For example, if they’ve mainly created apps that rely on real-time online data, they may not have delved into Core Data as a storage component for more complex projects. Or perhaps they’ve never had to implement more sophisticated graphics using a lower-level technology like Core Graphics.

A larger iOS project might benefit from a junior developer working on smaller tasks—for example, in a news reader app, they might be tasked with implementing a dark mode option—but when bugs arise, it may take the help of a mid-level or senior developer to navigate the project and troubleshoot effectively. This is especially true if their tasks affect multiple project components.

With between two and five years of experience in iOS development, a mid-level developer will have worked on several iOS apps from start to finish to publication, and learned valuable architectural lessons from their maintenance periods as well. They will likely know both Swift and Objective-C, along with several common iOS architectures, so that they can start making positive contributions soon after onboarding with most iOS codebases.

Mid-level developers will have likely implemented a greater variety of features, so they’ll be comfortable with more advanced technologies like Core Animation, Core Location, and Core ML. They’re used to taking ownership of entire features, whether that means integrating with third-party services, implementing custom user interface or user experience components, or creating novel solutions to address business- and app-specific challenges in projects of any size.

With at least five years of software development experience focused on iOS, a senior developer will have no trouble proving their reliability in delivering successful projects. Senior developers will know how—and more importantly, when—to use expert-level iOS developer skills like leveraging Grand Central Dispatch or optimizing graphics performance using iOS Metal. They have the Swift and Objective-C skill sets needed to maintain or even migrate an Objective-C project, and also to create a well-architected project in either language from scratch. They’ll have a deep familiarity with common iOS design patterns like MVC, MVVM, and VIPER, as well as common Apple frameworks like UIKit (and others provided by Cocoa Touch), AppKit, and SwiftUI. Good candidates will have the soft skills (especially the communication skills) needed to mentor developers, but they’ll also be comfortable collaborating with cross-functional teams and stakeholders to keep project requirements clear and easy to translate into actionable goals. Hire a senior developer with extensive experience if you don’t have one already for any mission-critical or complex iOS project.

In the end, projects and teams have their nuances, and the target experience level is up to you. When it’s not clear what you need, it’s worth consulting the senior developers on your team. If you don’t have any, hire iOS developers with the best track record you can find.

How to Write an iOS Developer Job Description for Your Project

With a rough list of requirements, especially technical ones, you can start customizing an iOS developer job description template. You may also want to incorporate elements from a Swift developer job description if it applies to your project. The more detail you’re able to include, the better—this way, candidates will self-filter more accurately, saving your time and theirs. But the job description has to be accurate to be effective, so it’s worth having someone close to the project check the final listing to make sure that you’re on the right track to hire iOS app developers who will best help your development team meet your business needs.

What Are the Most Important iOS Developer Interview Questions?

Interviewing and vetting applicants is easier if you have both a list of iOS developer interview questions and someone to help you understand your candidate’s answers. If your iOS project uses Swift, consider adding some Swift interview questions to the mix. It also makes sense to get less specific (while remaining appropriately technical) by including interview questions about mobile app development.

What does an iOS developer do?

It sounds simple enough, but a question like this can be a great icebreaker to kick off a conversation and begin to assess a candidate’s understanding of how their role fits into the bigger picture of an organization. An iOS developer primarily writes and maintains code in the Objective-C or Swift programming languages to build mobile applications for the iPhone. But to write that code in a way that aligns with your brand and business goals, an iOS developer’s daily tasks may overlap significantly with several other roles, depending on the size of your team. A skilled iOS developer should be able to draw upon their direct experiences interacting with these overlapping and adjacent roles: UI/UX designer, graphic designer, DevOps engineer, app publisher, project manager, team lead, marketer, software architect, back-end developer, network engineer, accessibility specialist, and security expert. However they approach your project, an iOS developer must be skilled at translating user requirements into functional, visually appealing, and on-brand mobile features.

If you were to choose between SwiftUI and UIKit for a greenfield project, which project aspects would you need to consider, and why?

This is a great question to ask to get a sense of the candidate’s decision-making process and experience with software architecture. SwiftUI, significantly newer but still mature, makes sense as a default choice for new iOS projects, especially if their feature set will be fairly standard. But an experienced developer should recognize that SwiftUI still lacks some features that the older UIKit has full support for. Apple is improving this situation incrementally, but for more complex or feature-rich projects (for example, those relying on concurrent programming), SwiftUI may come with an unnecessary development burden. A pragmatic candidate may propose a hybrid approach to benefit from the strengths of the two frameworks—especially SwiftUI’s speed in terms of both rapid application development and superior on-hardware runtime performance. That said, a brand-new project may still need to support older versions of iOS that will limit the use of certain features in newer versions of SwiftUI, in which case it isn’t a wise option.

How do you approach accessibility in iOS projects?

Accessibility should be one of the highest priorities in the development process—in fact, regulations may impose accessibility requirements on your project. Strong candidates should know their way around the XCode IDE’s Accessibility Inspector for initial auditing. They should be able to describe their experience with this feature, what they found helpful about it, and some of its limitations. They should also know how to make apps compatible with iOS accessibility features like VoiceOver, Voice Control, and Dynamic Type, and be able to provide examples of how accessibility has changed how they’ve approached UI label texts.

When should you use Apple’s Security framework?

Much like accessibility, security is of the utmost concern when building and maintaining any app that handles user data. The Security framework provides low-level functionality for security aspects like code signing, secure data storage and transportation, cryptography, and user authentication and authorization. But it’s not meant to be a catchall solution, or even the first choice when it comes to developer security considerations. A good answer will highlight that a higher-level framework should be used instead whenever possible. For example, developers tasked with implementing HTTPS functionality would use the URL Loading System API, which uses the Security framework, rather than just using the Security framework directly.

Why Do Companies Hire iOS Developers?

Regardless of industry, any company with a serious mobile strategy needs to offer an iOS-specific app, and therefore needs experienced iOS developers. Your company’s app may well be the primary way your clients interact with you; if so, keeping high standards for your app’s user experience is a crucial strategy for maintaining your organization’s reputation and profitability.

Whether launching a minimum viable product, optimizing an iOS app as it scales, or maintaining a legacy application, companies continue to fuel the demand for iOS developers. But as a hiring manager, you need to know your project’s specific technical needs before you can find a suitable iOS developer.

With the relevant topics and technologies from this guide at hand, you’re ready to start shaping your job description and narrowing your candidate pool. Hiring the right developer for your project will let you see firsthand how offering a professionally made iOS application can bolster your company’s success.