Kickstarter for iOS is the open source native iOS application that powers the Kickstarter platform, built in Swift using functional reactive programming patterns.
The app addresses the challenge of building a complex, feature-rich mobile experience while maintaining testability and clarity around side effects. It achieves this through view models that function as pure mappings of input signals to output signals, isolating business logic from UI concerns. The architecture embraces functional-reactive programming using ReactiveSwift and ReactiveCocoa, allowing the team to reason about data flow and state changes declaratively.
The project suits teams interested in learning functional reactive programming patterns in iOS development or studying how a production app at scale handles localization, accessibility, and comprehensive testing. The codebase contains nearly 600 snapshot tests covering various screens, languages, device types, and edge cases, making it valuable for understanding snapshot testing strategies. Developers should be aware that the project requires Xcode 14.3 with Swift 5.8, and a mock mode is available for development by setting a flag to serve hard-coded data. The README does not compare this approach to alternatives, but it does highlight the team's reliance on custom libraries like Prelude and ReactiveExtensions built on top of ReactiveSwift.
The project maintains active development with regular commits across multiple feature areas and consistent test coverage expansion. The codebase shows ongoing refinement of view model implementations and test infrastructure. Documentation is actively maintained through a separate native-docs repository, indicating sustained effort to keep guidance current. The team continues to iterate on the snapshot testing approach, adding new test cases for different language and device combinations.
