The CombineRx library contains a series of functions that help with the interoperability between RxSwift and Apple's Combine frameworks.
Interoperability between Combine and RxSwift
Combine to RxSwift
In order to convert Combine
Publishers to RxSwift
Observables, you can make use of the
asObservable() function. This can be done as follows:
import Combine import RxSwift import CombineRx let myBridgedObservable = Just(0).asObservable()
RxSwift to Combine
In order to convert RxSwift
Observables to Combine
Publishers, you can make use of the
asPublisher(withBufferSize:andBridgeBufferingStrategy:) function. This can be done as follows:
import Combine import RxSwift import CombineRx let myBridgedPublisher1 = Observable.just(0).asPublisher(withBufferSize: 1, andBridgeBufferingStrategy: .error) let myBridgedPublisher2 = Observable.from([0, 1, 2, 3]).asPublisher(withBufferSize: 4, andBridgeBufferingStrategy: .error)
One difference between RxSwift and Combine is that Combine adheres to the mechanism of backpressure in order to ensure that
Publishers only produce as many elements that
Subscribers have requested. This prevents the case where elements might build up in a
Publishers buffer faster than they can be processed downstream by a subscriber as this could lead to out-of-memory errors and degradation in performance due to high system resource consumption. Combine applies this backpressure upstream through a contractual obligation by
Publishers to only emit an element when it is requested by
Observables differ in this regard as they rely on a source with an unbounded rate of production and therefore when bridging to a Combine
Publisher, we must maintain a buffer or drop elements accordingly in order to satisfy the requirements of downstream subscribers.
This is the reason for the required
andBridgeBufferingStrategy parameters for
withBufferSize is where the buffer size should manually be set (ideally based directly on the number of expected elements in the sequence).
andBridgeBufferingStrategy is the strategy to employ when the maximum buffer capacity is reached. Keeping in line with native Combine strategies, this can either be
error, where any buffer overflow is treated as an error,
dropNewest where the elements already present in the buffer are maintained and any new elements are ignored, or finally
dropOldest where new elements are added to the buffer and replace older elements that were already present.
Additional information on Combine's use of backpressure can be found here.
It is currently possible to install this library using Swift Package Manager. In order to do so, please add the current repository as a package dependency using Xcode or include the following in your
import PackageDescription let package = Package( ... dependencies: [ .package(url: "https://github.com/Jackstone92/CombineRx", .upToNextMajor(from: "0.1.0")), ], ... targets: [ .target(name: "MyTarget", dependencies: ["CombineRx"]), ] )
Copywrite and license information
Copyright 2020 © Jack Stone
CombineRx is made available under the MIT License