How do I handle API calls in Katana?

Use side effects with promises or the async/await pattern via Hydra, as shown in the README examples. This allows you to dispatch state updaters after asynchronous operations complete, keeping logic testable.

Katana vs The Composable Architecture for iOS?

Katana is a Redux-inspired framework with built-in side effects and dependency injection, while TCA offers more modularity and composability. The README notes that Bending Spoons migrated to TCA for larger apps due to Katana's scalability limitations.

Can I use Katana with SwiftUI?

Katana is designed for UIKit and works best with Tempura for UI. While you can adapt it for SwiftUI, it's not directly integrated, so you may face friction compared to using SwiftUI's native @State or ObservableObject.

What are the best practices for state management in Katana?

Follow the Bending Spoons guidelines linked in the README, such as keeping state serializable, using pure updaters, and leveraging dependency injection for testability. This ensures maintainable and predictable code.

How to test side effects in Katana?

Mock dependencies using the built-in container in tests, as described in the dependency injection section. This allows you to isolate side effect logic and verify state changes without relying on external services.

Is Katana still actively maintained?

The README states that Bending Spoons has migrated to TCA for new projects, but Katana is stable and used in production. Check GitHub for recent updates, as maintenance might be limited compared to more active alternatives.

Open-Awesome

Katana

MITSwift0.8.0

A modern Swift framework for writing testable and predictable iOS app logic, inspired by Redux.

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What is Katana?

Katana is a Swift framework for building iOS applications with a predictable and testable architecture. It manages app state using a Redux-inspired pattern, where the entire state is centralized and can only be modified through dispatched StateUpdaters. This approach eliminates race conditions and makes business logic easy to reason about.

Target Audience

iOS developers building medium-sized applications who need a structured, testable approach to state management and business logic.

Value Proposition

Developers choose Katana for its strict unidirectional data flow, built-in side effect handling with promises, and excellent testability through dependency injection. It scales well for production apps and integrates seamlessly with UIKit via companion libraries like Tempura.

Overview

Swift Apps in a Swoosh! A modern framework for creating iOS apps, inspired by Redux.

Use Cases

Best For

Implementing Redux-like state management in Swift iOS apps
Building testable business logic with dependency injection
Managing complex side effects and asynchronous operations
Creating predictable state updates with pure functions
Profiling app performance with Signpost integration
Scaling iOS applications with a maintainable architecture

Not Ideal For

Large-scale applications requiring highly modular and composable architecture
Teams heavily invested in SwiftUI who prefer native state management solutions
Projects needing rapid prototyping with minimal boilerplate and setup
Apps that prioritize reactive programming patterns like Combine over Redux-style unidirectional flow

Pros & Cons

Pros

Predictable State Updates

Centralized state and pure StateUpdaters enforce unidirectional data flow, eliminating race conditions as highlighted in the README's philosophy on predictability.

Testable Business Logic

Built-in dependency injection container allows mocking of dependencies, making side effects and state updaters easy to test in isolation, improving code quality.

Async Side Effects

Side effects leverage promises and async/await patterns via Hydra, simplifying asynchronous operations like API calls with clear error handling, as demonstrated in the code examples.

Performance Profiling

Integrated Signpost API provides detailed instrumentation in Instruments for monitoring dispatched items, aiding in performance optimization for production apps.

Cons

Modularity Challenges

The README admits that for growing applications, Katana's architecture can become less modular, leading its creators to migrate to The Composable Architecture for better scalability.

UI Integration Overhead

Katana requires companion libraries like Tempura for UI synchronization, adding complexity compared to native SwiftUI state management or other lightweight solutions.

Ecosystem Limitations

With the creators moving to TCA, community support and updates may lag, and the ecosystem is less mature compared to more popular state management libraries in Swift.

Frequently Asked Questions

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