ios – 如何使用ReactiveCocoa 3实现基本的UITextField输入UIButton操作场景？

我同时是一个 Swift和ReactiveCocoa noob.使用MVVM和Reactive Cocoa v3.0-beta.4框架,我想实现此设置,以了解新RAC 3框架的基础知识.

我有一个文本字段,我希望文本输入包含超过3个字母,以进行验证.如果文本通过验证,则应启用下面的按钮.当按钮收到触地事件时,我想使用视图模型的属性触发操作.

由于目前关于RAC 3.0测试版的资源非常少,我通过阅读框架的Github repo上的QA来实现以下内容.这是我到目前为止所能提出的：

viewmodel.swift

class viewmodel {

    var text = MutableProperty<String>("")
    let action: Action<String,Bool,NoError>
    let validatedTextProducer: SignalProducer<AnyObject?,NoError>

    init() {
        let validation: Signal<String,NoError> -> Signal<AnyObject?,NoError> = map ({
            string in
            return (count(string) > 3) as AnyObject?
        })

        validatedTextProducer = text.producer.lift(validation)

        //Dummy action for Now. Will make a network request using the text property in the real app. 
        action = Action { _ in
            return SignalProducer { sink,disposable in
                sendNext(sink,true)
                sendCompleted(sink)
            }
        }
    }
}

ViewController.swift

class ViewController: UIViewController {

    private lazy var txtField: UITextField = {
        return createTextFieldAsSubviewOfView(self.view)
    }()

    private lazy var button: UIButton = {
        return createButtonAsSubviewOfView(self.view)
    }()

    private lazy var buttonEnabled: DynamicProperty = {
       return DynamicProperty(object: self.button,keyPath: "enabled")
    }()

    private let viewmodel = viewmodel()
    private var cocoaAction: CocoaAction?

    override func viewDidLoad() {
        super.viewDidLoad()
        view.setNeedsUpdateConstraints()

        bindSignals()
    }

    func bindSignals() {
        viewmodel.text <~ textSignal(txtField)
        buttonEnabled <~ viewmodel.validatedTextProducer

        cocoaAction = CocoaAction(viewmodel.action,input:"Actually I don't need any input.")
        button.addTarget(cocoaAction,action: CocoaAction.selector,forControlEvents: UIControlEvents.TouchDown)

        viewmodel.action.values.observe(next: {value in
            println("view model action result \(value)")
        })
    }

    override func updateViewConstraints() {
        super.updateViewConstraints()

        //Some autolayout code here
    }
}

RACUtilities.swift

func textSignal(textField: UITextField) -> SignalProducer<String,NoError> {
    return textField.rac_textSignal().toSignalProducer()
        |> map { $0! as! String }
        |> catch {_ in SignalProducer(value: "") }
}

使用此设置,当视图模型的文本超过3个字符时,该按钮将启用.当用户点击按钮时,视图模型的动作运行,我可以将返回值设置为true.到现在为止还挺好.

我的问题是：在视图模型的操作中,我想使用其存储的文本属性并更新代码以使用它来发出网络请求.所以,我不需要视图控制器端的输入.我怎么能不要求我的Action属性输入？

cocoaAction = CocoaAction(viewmodel.action)

class viewmodel {

    var text = MutableProperty<String>("")
    let action: Action<AnyObject?,NoError>

    // if you want to provide outside access to the property
    var textValid: PropertyOf<Bool> {
        return PropertyOf(_textValid)
    }

    private let _textValid = MutableProperty(false)

    init() {
        let validation: Signal<String,NoError> -> Signal<Bool,NoError> = map { string in
            return count(string) > 3
        }

        _textValid <~ text.producer |> validation

        action = Action(enabledIf:_textValid) { _ in
            //...
        }
    }
}

func bindSignals() {
    buttonEnabled <~ viewmodel.action.enabled.producer |> map { $0 as AnyObject }
    //...
}