CombineAsync

CombineAsync is a collection of Combine extensions and utilities designed for asynchronous tasks.

Example

To run the example project, clone the repo, and run pod install from the Example directory first.

Requirements

• Swift 5.5 or higher
• iOS 13.0 or higher
• MacOS 10.15 or higher
• TVOS 13.0 or higher
• WatchOS 8.0 or higher
• Xcode 13 or higher

Installation

CocoaPods

You can easily install CombineAsync via CocoaPods. Add the following line to your Podfile:

pod 'CombineAsync', '~> 2.0'

Swift Package Manager (Xcode)

To install using Xcode's Swift Package Manager, follow these steps:

• Go to File > Swift Package > Add Package Dependency
• Enter the URL: https://github.com/hainayanda/CombineAsync.git
• Choose Up to Next Major for the version rule and set the version to 1.6.0.
• Click "Next" and wait for the package to be fetched.

Swift Package Manager (Package.swift)

If you prefer using Package.swift, add CombineAsync as a dependency in your Package.swift file:

dependencies: [
    .package(url: "https://github.com/hainayanda/CombineAsync.git", .upToNextMajor(from: "1.6.0"))
]

Then, include it in your target:

 .target(
    name: "MyModule",
    dependencies: ["CombineAsync"]
)

Usage

CombineAsync provides various extensions and utilities for working with Combine and Swift async. Here are some of the key features:

Publisher to Async

Convert any object that implements Publisher into Swift async with a single call:

// Implicitly await with a 30-second timeout
let result = await publisher.sinkAsynchronously()

// Specify a timeout explicitly
let timedResult = await publisher.waitForOutput(timeout: 1)

// No timeout
let noTimeoutResult = await publisher.waitForOutputIndefinitely()

Sequence of Publisher to an Array of Output

Convert a sequence of Publisher into async with a single call:

// Implicitly await with a 30-second timeout
let results = await arrayOfPublishers.sinkAsynchronously()

// Specify a timeout
let timedResults = await arrayOfPublishers.waitForOutputs(timeout: 1)

// No timeout
let noTimeoutResult = await arrayOfPublishers.waitForOutputsIndefinitely()

Future from Async

Convert Swift async code into a Future object with ease:

let future = Future { 
    try await getSomethingAsync()
}

Publisher Async Sink

Execute asynchronous code inside a sink without explicitly creating a Task:

publisher.asyncSink { output in
    await somethingAsync(output)
}

withCheckedThrowingContinuation with timeout

Convert old asynchronous code using withCheckedThrowingContinuation with timeout:

// Automatically fail after 30 seconds
try await withCheckedThrowingContinuation(timeout: 30) { continuation in
    doLongOperation { result in
        continuation.resume(returning: result)
    }
}

Publisher Debounce Async Sink

Execute asynchronous code inside a sink and make it debounced if its still running asyncrhonous task:

publisher.debounceAsyncSink { output in
    await somethingAsync(output)
}

Auto Release Sink

Automatically release a closure in the sink after a specified duration or when an object is released:

publisher.autoReleaseSink(timeout: 60) { _ in
    // Handle completion
} receiveValue: { 
    // Handle value reception
}

Weak and Auto Release Assign

Assign without retaining the class instance by using autoReleaseAssign or weakAssign instead of assign:

// with cancellable
let cancellable = publisher.weakAssign(to: \.property, on: object)

// with auto release cancellable
publisher.autoReleaseAssign(to: \.property, on: object)

Publisher error recovery

Recover from errors using three different methods:

// Ignore errors and produce AnyPublisher<Output, Never>
publisher.ignoreError()

// Convert errors to output and produce AnyPublisher<Output, Never>
publisher.replaceError { error in convertErrorToOutput(error) }

// Attempt to convert errors to output and produce AnyPublisher<Output, Failure>
publisher.replaceErrorIfNeeded { error in convertErrorToOutputIfNeeded(error) }

Publisher Async Map

Map asynchronously using CombineAsync:

publisher.asyncMap { output in
    await convertOutputAsynchronously(output)
}

There are some async map method you can use:

• asyncMap which is equivalent with map but asynchronous
• asyncTryMap which is equivalent with tryMap but asynchronous
• asyncCompactMap which is equivalent with compactMap but asynchronous
• asyncTryCompactMap which is equivalent with tryCompactMap but asynchronous

Publisher Map Sequence

Map elements of a Publisher with a Sequence as its output:

myArrayPublisher.mapSequence { element in
    // Map the element of the sequence to another type
}

Those line of code are equivalent with:

myArrayPublisher.map { output in
    output.map { element in
        // do map the element of the sequence to another type
    }
}

All of the sequence mapper that you can use are:

• mapSequence(_:) which bypass Sequence.map(_:)
• compactMapSequence(_:) which bypass Sequence.compactMap(_:)
• tryMapSequence(_:) which bypass Sequence.map(_:) but with throwing mapper closure
• tryCompactMapSequence(_:) which bypass Sequence.compactMap(_:) but with throwing mapper closure
• asyncMapSequence(_:) which bypass Sequence.asyncMap(_:)
• asyncCompactMapSequence(_:) which bypass Sequence.asyncCompactMap(_:)

Contribute

Feel free to contribute by cloning the repository and creating a pull request.

Author

Nayanda Haberty, hainayanda@outlook.com

License

CombineAsync is available under the MIT license. See the LICENSE file for more info.