james-jasenia/operators-and-bindings-swift-frameworks

operators-and-bindings-swift-frameworks

RxSwift

BehaviorSubject vs BehaviorRelay - .values vs .value

A subject has a values property of type AsyncThrowingStream<Element, Error> and a relay has a public value property which is a !try of a subjects element. This kinda makes sense as subjects can be terminate which means that an emission might not be a value. Relays cannot terminate so there should always be a value even if it is nil.

Combine

Deferred and Future

You need wrap Future in a Deferred block so that the Future will only be created upon subscription, otherwise, the Future will be created and excute it's work (common use case is a network request) before anything is observing it. This setup will behave the same way a Single does in `RxSwift.

TODO:

• Create mapMany methods for ReactiveSwift and Combine observables. It probably wouldn't hurt to have a Foundation mapMany method as well.

extension ObservableType where Element: Collection {
    public func mapMany<Result>(_ transform: @escaping (Element.Element) throws -> Result) -> Observable<[Result]> {
        return map { collection -> [Result] in
            try collection.map(transform)
        }
    }
}