Breaking into iOS development can feel like stepping into an exclusive club with its own language, rituals, and unwritten rules. Whether you’re a seasoned developer transitioning from Android or web development, or you’re just starting your coding journey, understanding the unique culture and best practices of iOS development is essential for success.
The iOS ecosystem isn’t just about writing Swift code and submitting apps to the App Store. It’s about embracing a philosophy that prioritizes user experience, respects Apple’s design principles, and navigates the sometimes-mysterious App Review process. Experienced iOS developers have learned these lessons through trial, error, and countless hours debugging issues that seemed impossible to solve.
This guide distills the collective wisdom of the iOS development community into the fundamental rules that separate amateur projects from professional applications. Some of these rules are technical necessities, while others represent the cultural knowledge that makes you a better member of the iOS development ecosystem. By understanding and following these principles, you’ll not only build better apps but also save yourself from common pitfalls that trip up newcomers.
Let’s explore the essential rules that every successful iOS developer has internalized.
Human Interface Guidelines Are Your Bible
Apple’s Human Interface Guidelines (HIG) aren’t suggestions—they’re the foundation of iOS app design. These guidelines represent years of research into how people interact with their devices and what creates intuitive experiences.
Experienced developers study the HIG thoroughly before designing any interface element. They understand that Apple has tested these patterns with millions of users, and deviating from them usually means creating friction for your users. When you use standard UI components in expected ways, users already know how to interact with your app because they’ve used similar patterns in dozens of other iOS apps.
This doesn’t mean every app should look identical. The HIG provides a framework within which you can express creativity while maintaining usability. Think of it like grammar rules in writing—you need to master them before you can effectively break them for artistic effect.
The guidelines cover everything from button placement to animation timing to color contrast ratios for accessibility. Ignoring these details might seem minor during development, but users notice when something feels “off,” even if they can’t articulate why.
App Review Rejections Are Part of the Process
Every iOS developer has experienced the sinking feeling of opening an App Review rejection email. It’s not a matter of if, but when. Even apps from experienced teams at major companies get rejected regularly.
The key is understanding that App Review isn’t adversarial—it’s Apple’s quality control mechanism. Reviewers are protecting users from malicious apps, privacy violations, and poor experiences. When your app gets rejected, read the rejection notice carefully. Apple’s reviewers typically provide specific guidance about what needs to change.
Common rejection reasons include incomplete functionality in the submitted build, privacy policy issues, undisclosed data collection, misleading app descriptions, or using private APIs. Smart developers proactively audit their apps against the App Store Review Guidelines before submission, catching potential issues early.
Building a good relationship with App Review matters. Respond professionally to rejection notices, make the requested changes promptly, and use the resolution center to ask clarifying questions when guidelines seem ambiguous. Remember that reviewers are people doing their jobs, not obstacles to overcome.
Many developers maintain a pre-submission checklist covering common rejection reasons, which significantly reduces review delays.
SwiftUI vs. UIKit: Know Both
The iOS development community has been navigating the transition from UIKit to SwiftUI since 2019, and the honest truth is that you need to understand both frameworks for the foreseeable future.
SwiftUI represents Apple’s vision for the future of iOS development. Its declarative syntax makes building interfaces faster and more intuitive, especially for common patterns. The automatic handling of state changes reduces boilerplate code significantly. For new projects targeting recent iOS versions, SwiftUI often provides the fastest path to a working interface.
However, UIKit isn’t dead—not even close. Millions of lines of production code use UIKit, and many companies maintain UIKit-based apps that need regular updates and new features. Some advanced functionality still requires dropping into UIKit, and certain performance-critical scenarios work better with UIKit’s imperative approach.
A professional iOS app developer learns SwiftUI’s strengths while maintaining their UIKit skills. They know when each framework is appropriate and how to bridge between them when necessary. Understanding both also helps when reading documentation, since many resources still reference UIKit patterns.
The ability to work comfortably in both frameworks makes you significantly more valuable to employers and clients.
Memory Management Still Matters
Despite Automatic Reference Counting (ARC) handling most memory management automatically, understanding retain cycles and memory leaks remains critical for iOS developers.
The most common memory issue in iOS apps is the strong reference cycle, where two objects hold strong references to each other, preventing ARC from deallocating either one. This typically happens with closures that capture self without using weak or unowned references appropriately.
Experienced developers instinctively use [weak self] or [unowned self] in closures when appropriate. They understand the difference between these modifiers and when each is suitable. They also use Xcode’s memory debugging tools to profile their apps and identify leaks before they reach production.
Memory issues might not crash your app immediately, but they degrade performance over time as your app accumulates objects that should have been deallocated. Users notice when apps become sluggish or drain their battery, even if they don’t understand the technical reasons.
Good memory hygiene also involves properly cleaning up observers, timers, and delegates when objects are deallocated.
Testing Isn’t Optional
Professional iOS developers write tests. XCTest, Apple’s testing framework, should be as familiar to you as UIKit or SwiftUI.
Unit tests verify that your business logic works correctly in isolation. They catch regressions when you modify existing code and document how your functions are supposed to behave. Well-written tests serve as executable documentation that stays current with your codebase.
UI tests automate interactions with your app’s interface, verifying that user flows work end-to-end. While UI tests are slower and more fragile than unit tests, they catch integration issues that unit tests miss.
Many developers follow the testing pyramid principle: lots of fast unit tests, fewer integration tests, and a small number of comprehensive UI tests. This balance provides good coverage without making your test suite too slow to run frequently.
Continuous integration systems can run your test suite automatically on every commit, catching issues before they reach reviewers or users. The time invested in writing tests pays dividends by preventing bugs and enabling confident refactoring.
Privacy Is Non-Negotiable
Apple has made privacy a central part of its brand identity, and the App Store reflects this priority. iOS developers must take data privacy seriously, not just as a compliance exercise but as a core design principle.
Before collecting any user data, ask yourself if you genuinely need it. Minimize data collection to only what’s necessary for your app’s functionality. When you do collect data, be transparent about what you’re collecting and why.
The App Privacy section on the App Store requires detailed disclosure of data practices. Developers must accurately describe what data they collect, whether it’s linked to users’ identities, and how it’s used. Misrepresenting your data practices can result in app removal.
iOS provides APIs for requesting permission before accessing sensitive information like location, photos, camera, and microphone. Always request these permissions with clear, user-friendly descriptions of why you need them. Generic permission requests like “App would like to access your photos” without explanation feel invasive and users will often deny them.
Strong privacy practices build user trust, which translates into better reviews and more loyal users.
Performance Optimization Starts Early
Smooth performance isn’t something you bolt on at the end—it’s a quality you build in from the beginning. Users expect iOS apps to feel responsive, with smooth scrolling and instant reactions to touches.
The 60 frames per second standard means you have roughly 16 milliseconds to complete all work for each frame. Any operation that exceeds this budget causes dropped frames and janky animations that users immediately notice.
Experienced developers profile their code regularly using Instruments, Apple’s performance analysis tool. They identify expensive operations happening on the main thread and move them to background queues. They optimize image loading and display, implement efficient data structures, and avoid premature optimization while remaining aware of performance implications.
TableView and CollectionView cell reuse is a classic iOS performance pattern that every developer must understand. Loading images asynchronously and caching them properly prevents scrolling stutters. Lazy loading of data as users scroll (infinite scroll or pagination) keeps memory usage reasonable.
Small performance considerations throughout development prevent the need for major optimization work later.
Version Control Is Professional Hygiene
Git is the universal standard for iOS development, and every professional developer must be comfortable with it. Using version control isn’t just about tracking changes—it enables collaboration, experimentation, and recovery from mistakes.
Commit frequently with clear, descriptive messages that explain what changed and why. Organize your work into logical commits rather than dumping hours of changes into a single “stuff” commit. Use branches for new features and experiments, keeping your main branch stable.
Understanding merge conflicts and how to resolve them confidently is essential, especially when working on teams. Pull requests and code reviews improve code quality and spread knowledge across your team.
Git also enables you to try risky refactoring with confidence. If your experiment breaks something, you can always revert to a working state. This safety net encourages healthy experimentation and learning.
Many iOS developers use GitHub, GitLab, or Bitbucket for remote repositories, enabling collaboration and providing backup for their code.
The Simulator Isn’t Enough
Xcode’s iOS Simulator is invaluable during development, but it’s not a real device. Relying exclusively on the simulator will result in unpleasant surprises when you finally test on actual hardware.
The simulator runs on your Mac’s processor, which is significantly more powerful than mobile chips. Performance that feels smooth in the simulator might be sluggish on older devices. Memory constraints differ as well—your Mac has far more RAM than an iPhone.
Networking behavior varies between the simulator and real devices. Testing on actual hardware with real network conditions (including slow or unreliable connections) reveals issues the simulator masks.
Sensor APIs, camera functionality, and hardware features like Face ID work differently or not at all in the simulator. Push notifications require physical devices for complete testing.
Experienced developers maintain a collection of test devices representing different iOS versions and form factors. Testing on real hardware throughout development, not just before release, catches problems early when they’re easier to fix.
Documentation and Comments Serve Different Purposes
Good developers document their code thoughtfully, understanding the distinction between comments and documentation.
Comments explain why code does something when the reason isn’t obvious from reading the code itself. They provide context about business logic, explain workarounds for system bugs, or clarify complex algorithms. Comments should not simply restate what the code does—that’s redundant and clutters the codebase.
Documentation, typically written as specially-formatted comments that Xcode can parse, describes the public interface of your types and functions. It explains what parameters mean, what values functions return, and any important preconditions or side effects.
Swift’s strong typing reduces the need for some documentation—well-named types and parameters are self-documenting. A function named calculateTotalPrice(items: [CartItem], discountCode: String?) -> Decimal communicates its purpose clearly.
README files in your repositories should explain what the project is, how to build it, and any special setup requirements. This documentation helps new team members and your future self when you return to a project months later.
Accessibility Isn’t An Afterthought
Building accessible apps isn’t just ethically right—it’s also good business. Millions of iOS users rely on accessibility features like VoiceOver, Dynamic Type, and Voice Control.
UIKit and SwiftUI provide accessibility APIs that are straightforward to implement when you design with accessibility in mind from the start. Label interactive elements clearly, provide hints when gestures aren’t obvious, and ensure sufficient color contrast for users with vision impairments.
Supporting Dynamic Type means your text resizes appropriately when users change their preferred text size in system settings. This requires using dynamic fonts and testing your layouts at different sizes.
VoiceOver, iOS’s screen reader, requires semantic markup of your interface elements. Images need descriptions, buttons need labels, and related elements should be grouped logically.
Apple’s Accessibility Inspector helps you audit your app’s accessibility, identifying issues before users encounter them. Many accessibility improvements also benefit users without disabilities—clear labeling and logical organization help everyone.
Stay Current But Not Bleeding Edge
The iOS ecosystem moves quickly. New iOS versions arrive annually, Xcode updates come more frequently, and Swift continues evolving. Successful developers balance staying current with maintaining stability.
Adopting new iOS features immediately can provide competitive advantages and access to powerful new APIs. However, supporting older iOS versions remains necessary since many users don’t update immediately. Generally, supporting the current iOS version and the previous one covers the vast majority of users.
When Apple introduces new frameworks or languages features, take time to learn them through side projects before incorporating them into production apps. Understand the trade-offs and maturity level of new technologies.
Following iOS development blogs, podcasts, and Twitter accounts helps you stay informed without constantly context-switching. Apple’s WWDC session videos provide deep dives into new features directly from the engineers who built them.
Being current means understanding what’s possible, not necessarily using every new feature immediately.
Your Career Is Your Responsibility
The iOS development field rewards continuous learning and skill development. Technology changes rapidly, and developers who stop learning fall behind.
Build side projects to experiment with new technologies and practice skills. Contribute to open source projects to learn from experienced developers and give back to the community. Share your knowledge through blog posts, conference talks, or helping others on Stack Overflow.
Networking with other iOS developers through local meetups, conferences, or online communities provides learning opportunities and career connections. The iOS development community is generally welcoming and helpful to those who engage respectfully.
Don’t define yourself solely by the technologies you know. The principles of good software development—clean code, proper architecture, thorough testing—transcend any specific framework or language. These fundamentals make you a better developer regardless of what platforms you work on.
Bringing It All Together
These rules represent hard-won wisdom from developers who’ve shipped countless iOS apps. Some are technical requirements, others cultural expectations, but all contribute to building better apps and becoming a more professional developer.
Mastering iOS development takes time and practice. Don’t expect to internalize all these principles immediately. Focus on one or two areas where you’re weakest, improve them deliberately, then move on to the next challenge.
The iOS platform continues evolving, and new best practices emerge regularly. Stay curious, remain humble, and remember that even the most experienced developers are still learning. The rules outlined here provide a strong foundation, but your personal experience will teach you lessons specific to your projects and circumstances.
Now close this browser tab and start building something. The best way to become a better iOS developer is to write code, make mistakes, and learn from them.