Medium article: SLC part 1 - SignInView

SignInView.swift

final class SignInView: UIView {

    // Some loading view, it might contain a `UIActivityIndicatorView`
    // it has reactive binding for `isLoading`, but starts invisible
    private lazy var loadingView = LoadingView()

    // In fact these TextFields are some subclass capable of displaying validation errors
    private lazy var usernameField = UITextField()
    private lazy var passwordField = UITextField()
    private lazy var confirmPasswordField = UITextField()

    private lazy var signInButton = UIButton()
        .disabled() // button starts as disabled until form is valid

    private lazy var stackView = UIStackView(arrangedSubviews: [usernameField, passwordField, confirmPasswordField, signInButton])

    // Call some setupViews methods, which populates the view and sets up constraints
}

extension SignInView: ViewModelled {

    typealias ViewModel = SignInViewModel

    var inputFromView: ViewModel.Input.FromView {
        return ViewModel.Input.FromView(
            username: usernameField.rx.text.orEmpty.asDriver(),
            password: passwordField.rx.text.orEmpty.asDriver(),
            confirmPassword: confirmPasswordField.rx.text.orEmpty.asDriver(),
            signInTrigger: signInButton.rx.tap.asDriver()
        )
    }

    func populate(with viewModel: ViewModel.Output) -> [Disposable] {
        return [
            output.isSignInButtonEnabled.drive(signInButton.rx.isEnabled),
            output.isSigningIn.drive(loadingView.rx.isLoading),
            // Simple means of displaying a validation error, if any.
            output.usernameValidation.drive(usernameField.rx.validation),
            // Confirm password and password validation are aggregated and displayed in `passwordField`
            output.passwordValidation.drive(passwordField.rx.validation)
        ]
    }
}