An iOS app developer designs, develops, and maintains applications for Apple devices. They utilize programming languages like Swift and Objective-C, work within the iOS Software Development Kit (SDK) and Xcode IDE. They translate requirements into coding, collaborate with UI/UX designers for app interfaces, integrate APIs, and debug for performance optimization. They also ensure the apps are in line with Apple’s design principles and app review guidelines. Testing the app's functionality and usability, fixing bugs, and updating app features are also part of their role. Additionally, they work closely with stakeholders to understand and implement desired functionalities.