Entwine

Accessories for Apple's Combine Framework.

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About

Entwine consists of three libraries (over two repositories) to be used in conjuction with Apple's Combine framework:

• The Entwine Utilities library includes additional operators, subjects and utilities for working with Combine sequences. The package currently includes a ReplaySubject, a withLatest(from:) operator and a Publishers.Factory for rapidly defining publishers inline from any source.

  View the README for the Entwine Utilities Library

• The EntwineTest library consists of tools for verifying expected behavior of Combine sequences. It houses a TestScheduler that uses virtual time, a TestablePublisher that schedules a user-defined sequence of elements in absolute or relative time, and a TestableSubscriber that record a time-stamped list of events that can be compared against expected behavior.

  View the README for the EntwineTest Library

• The EntwineRx library is a small library maintained under a separate repository that contains bridging operators from RxSwift to Combine and vice versa making RxSwift and Combine work together seamlessly.

  View the README for the EntwineRx Library

Note: EntwineRx is maintained as a separate Swift package to minimize the SPM dependency graph.

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Quick start guide

Create Combine publishers from any source

Use the Publishers.Factory publisher from the Entwine package to effortlessly create a publisher that meets Combine's backpressure requirements from any source. Find out more about the Entwine Utilities library.

Inline publisher creation for PhotoKit authorization status:

import Entwine

let photoKitAuthorizationStatus = Publishers.Factory<PHAuthorizationStatus, Never> { dispatcher in
    let status = PHPhotoLibrary.authorizationStatus()
    dispatcher.forward(status)
    switch status {
    case .notDetermined:
        PHPhotoLibrary.requestAuthorization { newStatus in
            dispatcher.forward(newStatus)
            dispatcher.forward(completion: .finished)
        }
    default:
        dispatcher.forward(completion: .finished)
    }
    return AnyCancellable {}
}

Unit test Combine publisher sequences

Use the TestScheduler, TestablePublisher and TestableSubscriber to simulate Combine sequences and test against expected output. Find out more about the EntwineTest library

Testing Combine's map(_:) operator:

import XCTest
import EntwineTest
    
func testMap() {
    
    let testScheduler = TestScheduler(initialClock: 0)
    
    // creates a publisher that will schedule it's elements relatively, at the point of subscription
    let testablePublisher: TestablePublisher<String, Never> = testScheduler.createRelativeTestablePublisher([
        (100, .input("a")),
        (200, .input("b")),
        (300, .input("c")),
    ])
    
    let subjectUnderTest = testablePublisher.map { $0.uppercased() }
    
    // schedules a subscription at 200, to be cancelled at 900
    let results = testScheduler.start { subjectUnderTest }
    
    XCTAssertEqual(results.recordedOutput, [
        (200, .subscription),           // subscribed at 200
        (300, .input("A")),             // received uppercased input @ 100 + subscription time
        (400, .input("B")),             // received uppercased input @ 200 + subscription time
        (500, .input("C")),             // received uppercased input @ 300 + subscription time
    ])
}

Bridge your RxSwift view models to Combine and use with SwiftUI

First, make sure you add the EntwineRx Swift Package (located in an external repo) as a dependency to your project.

Example coming soon

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Requirements

Entwine sits on top of Apple's Combine framework and therefore requires Xcode 11 and is has minimum deployment targets of macOS 10.15, iOS 13, tvOS 13 or watchOS 6.

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Installation

Entwine is delivered via a Swift Package and can be installed either as a dependency to another Swift Package by adding it to the dependencies section of a Package.swift file or to an Xcode 11 project by via the File -> Swift Packages -> Add package dependency... menu in Xcode 11.

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Documentation

Documentation for each package is available at:

• Entwine Documentation (Operators, Publishers and Accessories)
• EntwineTest Documentation (Tools for testing Combine sequence behavior)
• EntwineRx Documentation (Bridging operators for RxSwift)

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Copyright and license

This project is released under the MIT license

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