The Hollywood library provides developers a simple API for tracking the state of an asynchronous Swift Structured Concurrency workflow, with optional progress reporting.
There are two core APIs: ContextualActor and WorkflowAction.
A ContextualActor asynchronously executes and publishes the result of a WorkflowAction that produces a type T. A ContextualActor transitions between ContextualActor/States, i.e. ready, busy, success, failure. The current state is available by reading/ observing the state property. This makes it super easy to tie in with SwiftUI.
A WorkflowAction is a simple command (think GoF command) implementation that asynchronously executes to produce a value T. A good way to think about this protocol is that it forces you to give a discoverable name (via a concrete type) to a top-level asynchronous function. For a large code base, with multiple developers contributing code, this enables discoverability, improves future maintenance, and just generally helps organize top-level reusable functions.
WorkflowActions are composable. This means it's super easy to stitch together WorkflowActions into a complex asynchronous execution graph. To further help with discoverability, maintenance, and progress reporting, you can lean on the CompositeWorkflowActionandUnitOfWork`.
Workflows that require tracking state changes:
- Fetching anything from a web service (JSON, images, etc.)
- Uploading anything to a web service.
- Performing SQLite database reads and writes.
- Long running computations.
Workflows that benefit from progress reporting:
- Downloading large files over a network.
- Decompressing/ compressing large files.
- Importing a large amount of data into a local persistent store (SQLite, Core Data, etc.)
- Long running computations.
The Hollywood-Demos repo contains several working examples (including the example above). Additional examples will be added in the future.
- GitHub OAuth sign-in workflow.
- iTunes Music search (with album artwork download example).
- Numerous progress reporting examples.
There are numerous unit tests showing how to use Hollywood, as well as showing techniques for unit testing asynchronous workflows.
- Swift 5.10+
- iOS 17+
- macOS 14+
To use the Hollywood library in a SwiftPM project simply add the following to your Package.swift file:
.package(url: "https://github.com/briancoyner/hollywood.git", branch: "main"),
.target(name: "<target>", dependencies: [
.product(name: "Hollywood", package: "hollywood")
]),
Finally, add import Hollywood as needed to your source files.
- More demos are in the works, so you should watch and/ star the Hollywood-Demos repo.
- Introduce HollywoodTestKit to make it easier for you to write asynchronous unit tests.
- Additional DocC documentation (there's a decent start, but it's far from great).
Hollywood is written and maintained by Brian Coyner.
Hollywood and HollywoodUI is released under the MIT License. See LICENSE for details.