RxUI

RxUI is inspired by SwiftUI. RxUI goal is to improve the developer experience of using RxSwift by allowing you to concentrate on the business logic instead of the low-level reactive code.

• You can express your business logic in a natural way using plain Swift properties and methods
• It makes it much easier to debug your views and view models. You can set breakpoints and query any of your view model state.
• It’s beginner-friendly. You don’t need to learn combineLatest, withLatestFrom and other complex stateful operators to use it. You don't need flatMap to send a network request.
• It is more efficient because you avoid creating massive observable chains

WARNING This is proof of concept.

RxObservableObject

You can think of RxObservableObject and RxPublished as analogs of SwiftUI ObservableObject and Published.

final class LoginViewModel: RxObservableObject {
    @RxPublished var email = ""
    @RxPublished var password = ""
    @RxPublished private(set) var isLoading = false

    var title: String {
        "Welcome, \(email)"
    }

    var isLoginButtonEnabled: Bool {
        isInputValid && !isLoading
    }

    private var isInputValid: Bool {
        !email.isEmpty && !password.isEmpty
    }

    func login() {
        isLoading = true
        DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(2)) {
            self.isLoading = false
        }
    }
}

Each RxObservableObject has objectWillChange relay. The relay is generated automatically and is automatically bound to all properties marked with @RxPublished property wrapper. This all happens in runtime using reflection and associated objects.

RxView

RxView is an analog of a SwiftUI View. There is, however, one crucial difference. In UIKit, views are expensive, can't recreate them each time. The is reflected in RxView design.

final class LoginViewController: UIViewController, RxView {
    private let model = LoginViewModel()

    override func viewDidLoad() {
        super.viewDidLoad()

        // ... add views on screen ...

        disposeBag.insert(
            emailTextField.rx.text.bind(to: model.$email),
            passwordTextField.rx.text.bind(to: model.$password),
            loginButton.rx.tap.subscribe(onNext: model.login)
        )

        bind(model) // Automatically registers for update
    }

    // Called automatically when model changes, but no more frequently than
    // once per render cycle.
    func refreshView() {
        titleLabel.text = model.title
        model.isLoading ? spinner.startAnimating() : spinner.stopAnimating()
        loginButton.isEnabled = model.isLoginButtonEnabled
    }
}

When you call bind() method that accepts RxObservableObject it automatically registers for its updates (objectWillChange property). When the object is changed, refreshView() is called automatically. RxView hooks into the display system such that refreshView called only once per one render cycle.

License

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