Async
A Swift library providing syntactic sugar for Grand Central Dispatch (GCD) with chainable async blocks and modern queue support.
What is Async?
Async is a Swift library that provides syntactic sugar for Grand Central Dispatch (GCD), Apple's concurrency framework. It simplifies writing asynchronous code by offering a chainable syntax that reduces nesting and improves readability compared to raw GCD calls. The library supports modern quality-of-service queues, delayed execution, cancellation, and group operations.
iOS, macOS, tvOS, and watchOS developers working with Swift who need to manage asynchronous tasks using Grand Central Dispatch but want cleaner, more maintainable code.
Developers choose Async because it dramatically reduces the boilerplate and nesting associated with GCD, offering a fluent API that makes asynchronous code easier to write, read, and reason about while retaining full compatibility with Apple's concurrency system.
Overview
Syntactic sugar in Swift for asynchronous dispatches in Grand Central Dispatch
Use Cases
Best For
- Simplifying complex chains of asynchronous operations in Swift apps
- Reducing callback nesting when using Grand Central Dispatch
- Managing parallel tasks with groups and waiting for completion
- Dispatching delayed tasks with clean syntax
- Writing cross-platform async code for iOS, macOS, tvOS, and watchOS
- Integrating custom dispatch queues with system queues seamlessly
Not Ideal For
- Projects adopting Swift 5.5+ and its native async/await concurrency model
- Teams requiring actively maintained libraries with regular updates and bug fixes
- Applications needing sophisticated error handling or complex asynchronous patterns beyond basic chaining
- Developers who prefer to minimize external dependencies and use raw GCD or Swift concurrency directly
Pros & Cons
Pros
Eliminates deep nesting by allowing sequential async operations to be written in a fluent, readable chain, as shown in the README's comparison with raw GCD.
Provides shorthand methods for all GCD QoS queues (main, userInteractive, etc.) and custom queues, simplifying dispatch code.
AsyncGroup makes it easy to run and wait for multiple asynchronous blocks in parallel, improving code structure for concurrent tasks.
Built-in support for scheduling blocks after delays and canceling undispatched tasks offers better control over async workflows.
Cons
Explicitly marked as no longer maintained, meaning no future updates, bug fixes, or compatibility with new Swift versions.
Relies solely on GCD and does not integrate with Swift's modern async/await features, limiting its relevance for current development.
The README admits bugs with modern GCD queues in the iOS Simulator, which can impede testing and development.
Cancellation only applies to blocks not yet dispatched, which may not suffice for more advanced task management needs.
Frequently Asked Questions
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