Reactive UIViewController

ReactiveViewController.swift

class BaseViewController: UIViewController {

    // MARK: - Observers

    // MARK: View Trigger Observers

    private let viewWillAppearObserver: Signal<Void, NoError>.Observer
    private let viewDidAppearObserver: Signal<Void, NoError>.Observer
    private let viewWillDisappearObserver: Signal<Void, NoError>.Observer
    private let viewDidDisappearObserver: Signal<Void, NoError>.Observer

    // MARK: - Producers

    // MARK: View Event Producers

    private let viewWillAppearProducer: SignalProducer<Void, NoError>
    private let viewDidAppearProducer: SignalProducer<Void, NoError>
    private let viewWillDisappearProducer: SignalProducer<Void, NoError>
    private let viewDidDisappearProducer: SignalProducer<Void, NoError>

    // MARK: - Signals

    lazy var viewWillAppearSignal: Signal<Void, NoError> = { [unowned self] in
        var extractedSignal: Signal<Void, NoError>!
        self.viewWillAppearProducer.startWithSignal { signal, _ in
            extractedSignal = signal
        }
        return extractedSignal
    }()

    lazy var viewDidAppearSignal: Signal<Void, NoError> = { [unowned self] in
        var extractedSignal: Signal<Void, NoError>!
        self.viewDidAppearProducer.startWithSignal { signal, _ in
            extractedSignal = signal
        }
        return extractedSignal
    }()

    lazy var viewWillDisappearSignal: Signal<Void, NoError> = { [unowned self] in
        var extractedSignal: Signal<Void, NoError>!
        self.viewWillDisappearProducer.startWithSignal { signal, _ in
            extractedSignal = signal
        }
        return extractedSignal
    }()

    lazy var viewDidDisappearSignal: Signal<Void, NoError> = { [unowned self] in
        var extractedSignal: Signal<Void, NoError>!
        self.viewDidDisappearProducer.startWithSignal { signal, _ in
            extractedSignal = signal
        }
        return extractedSignal
    }()

    // MARK: - Initialization

    required init?(coder aDecoder: NSCoder) {
        (viewWillAppearProducer, viewWillAppearObserver) = SignalProducer.buffer(1)
        (viewDidAppearProducer, viewDidAppearObserver) = SignalProducer.buffer(1)
        (viewWillDisappearProducer, viewWillDisappearObserver) = SignalProducer.buffer(1)
        (viewDidDisappearProducer, viewDidDisappearObserver) = SignalProducer.buffer(1)
        super.init(coder: aDecoder)
    }

}

extension BaseViewController {
    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
        viewWillAppearObserver.sendNext()
    }

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        viewDidAppearObserver.sendNext()
    }

    override func viewWillDisappear(animated: Bool) {
        super.viewWillDisappear(animated)
        viewWillDisappearObserver.sendNext()
    }

    override func viewDidDisappear(animated: Bool) {
        super.viewDidDisappear(animated)
        viewDidDisappearObserver.sendNext()
    }
}