How do I convert a completion handler to a Future in FutureKit?

Wrap your async logic in a Promise, complete it with success or failure based on the operation, and return the promise's future. The README shows an example with iBuildStuffWithFutures() where a Promise is used to handle dispatch queues.

FutureKit vs PromiseKit: which should I use?

FutureKit is Swift-native with a focus on type safety and Executors for GCD, while PromiseKit has broader historical usage and cross-platform support. Choose FutureKit for pure Swift Apple projects wanting tight GCD integration, or PromiseKit for more community resources and compatibility.

Can FutureKit handle cancellations in async chains?

Yes, FutureKit provides clear cancellation semantics with automatic propagation through composed futures. Consumers can control whether to be notified of cancellations, as described in the cancellation support feature.

What are Executors and how do I use them?

Executors are an enumeration in FutureKit that simplify GCD queues, such as .Main for UI updates or .UserInitiated for intensive tasks. Use them in handlers like onSuccess to specify the execution context without manual dispatch_async.

Is FutureKit compatible with SwiftUI?

Yes, FutureKit can be used with SwiftUI by handling futures in view models or using onSuccess with .Main executor to update @State properties, but it requires manual integration since it's not specifically designed for SwiftUI's reactive patterns.

How does error handling work in FutureKit?

Errors are caught and propagated through future chains via onError handlers. You can attach a single error handler at the end to catch any error from preceding operations, aligning with Swift's native error handling for cleaner code.

FutureKit — Swift Future/Promises Library

What is FutureKit?

FutureKit is a Swift library that implements Futures and Promises for iOS and macOS development. It simplifies asynchronous and multi-threaded programming by providing a type-safe, composable way to handle async operations, errors, and cancellations. It solves the complexity of managing dispatch queues, callback blocks, and error propagation in traditional async code.

Target Audience

iOS and macOS developers building apps that require handling asynchronous operations, such as network calls, image processing, or database interactions, and who want cleaner, more maintainable async code.

Value Proposition

Developers choose FutureKit because it offers a unified, Swift-native approach to async programming with strong type safety, easy error handling, and built-in support for cancellation. Its Executor system abstracts away GCD complexities, making it easier to guarantee code runs on the correct queues without manual dispatch_async calls.

A Swift based Future/Promises Library for IOS and OS X.

Use Cases

Best For

Simplifying complex chains of asynchronous operations in Swift apps
Handling errors across multiple async steps with a single error handler
Managing cancellation cleanly in async workflows
Ensuring type safety when transforming async results (e.g., NSData to JSON to model objects)
Abstracting different async APIs (e.g., NSURLSession, AlamoFire) into a consistent interface
Writing async code that is easy to read and maintain without nested callbacks

Not Ideal For

Projects already using Apple's Combine framework for reactive async patterns
Teams preferring minimal dependencies for basic async tasks with completion handlers
Cross-platform Swift applications requiring async support on non-Apple operating systems
Apps with simple, linear async operations where Futures/Promises add unnecessary abstraction

Pros & Cons

Pros

Type-Safe Async Logic

Uses Swift Generics to enforce type safety, allowing the compiler to infer return types from asynchronous operations, as demonstrated in the README's image processing example from Future<UIImage> to blurred images.

Unified Error Handling

Integrates seamlessly with Swift's error handling, enabling a single catch-all error handler for entire chains of async operations, simplifying debugging and reliability, as highlighted in the error handling features.

Composable Future Chains

Futures can be easily mapped and composed into new Futures, with errors and cancellations automatically propagated, making complex async workflows manageable without nested callbacks.

GCD Simplification via Executors

Abstracts Grand Central Dispatch with Executors like .Main and .UserInitiated, ensuring code runs on specified queues without manual dispatch_async calls, as outlined in the GCD simplification section.

Cons

Apple-Platform Exclusive

Tailored specifically for iOS and macOS, limiting its utility for Swift projects targeting Linux, Windows, or other platforms where Swift is supported, as noted in the platform compatibility.

No Native Async/Await Support

Does not leverage Swift 5.5's built-in async/await syntax, which might make it feel outdated compared to modern Swift concurrency approaches, and the README doesn't mention plans for integration.

Additional Dependency Overhead

Introduces an external library dependency, which could be a drawback for teams aiming to keep their project's third-party code to a minimum, especially for simple async needs.

What is FutureKit?

Target Audience

Value Proposition

Use Cases

Best For

Simplifying complex chains of asynchronous operations in Swift apps
Handling errors across multiple async steps with a single error handler
Managing cancellation cleanly in async workflows
Ensuring type safety when transforming async results (e.g., NSData to JSON to model objects)
Abstracting different async APIs (e.g., NSURLSession, AlamoFire) into a consistent interface
Writing async code that is easy to read and maintain without nested callbacks

Not Ideal For

Projects already using Apple's Combine framework for reactive async patterns
Teams preferring minimal dependencies for basic async tasks with completion handlers
Cross-platform Swift applications requiring async support on non-Apple operating systems
Apps with simple, linear async operations where Futures/Promises add unnecessary abstraction

Pros & Cons

Pros

Type-Safe Async Logic

Unified Error Handling

Composable Future Chains

Futures can be easily mapped and composed into new Futures, with errors and cancellations automatically propagated, making complex async workflows manageable without nested callbacks.

GCD Simplification via Executors

Cons

Apple-Platform Exclusive

Tailored specifically for iOS and macOS, limiting its utility for Swift projects targeting Linux, Windows, or other platforms where Swift is supported, as noted in the platform compatibility.

No Native Async/Await Support

Does not leverage Swift 5.5's built-in async/await syntax, which might make it feel outdated compared to modern Swift concurrency approaches, and the README doesn't mention plans for integration.

Additional Dependency Overhead

Introduces an external library dependency, which could be a drawback for teams aiming to keep their project's third-party code to a minimum, especially for simple async needs.

FutureKit

What is FutureKit?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?

FutureKit

What is FutureKit?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?