每当ReactiveCocoa 5中的UITextField文本属性发生更改时，如何获取信号

Question

如何从用户启动和以编程方式更改UITextField text属性获得信号？通过使用continuousTextValues，仅在用户启动更改时报告信号。如果以编程方式设置textField.text，则不会触发信号。

这就是我使用continuousTextValues的方式：

textField.reactive.continuousTextValues.observeValues { value in
    print("Value: \(value)")
}

如果我手动设置text，它不会被触发：

textField.text = "Test"

Answer 1

信号continuousTextValues将仅在用户使用键盘输入时触发。您可以尝试这样做：

var characters = MutableProperty("")

tf.reactive.text <~ characters
tf.reactive.continuousTextValues.observeValues { [weak characters = characters] (text) in
   characters?.value = text!
}
tf.reactive.textValues.observeValues { [weak characters = characters] (text) in
   characters?.value = text!
}

characters.producer.skip(while: { $0.isEmpty }).startWithValues { (text) in
   log.debug("text = \(text)")
}

characters.value = "shaw"

Answer 2

您不必使用textField.text更改文本值，而是必须创建信号，将其绑定到文本字段并修改信号的值。我使用了Signal管道但是如果你需要存储以编程方式更改的值，你可以使用MutableProperty。

class MyViewController: UIViewController {
    var textField: UITextField!
    private let textFieldValuePipe = Signal<String?, NoError>.pipe()
    var textFieldValueSignal: Signal<String?, NoError>!

    override func viewDidLoad() {
        // Initialize the text field
        // ...

        // Bind the text of the text field to the signal pipe's output
        textField.reactive.text <~ textFieldValuePipe.output

        // A signal of text values emitted by the text field upon end of editing.
        let textFieldValuesSignal = textField.reactive.textValues

        // A signal of text values emitted by the text field upon any changes.
        let textFieldContinuousValuesSignal = textField.reactive.continuousTextValues

        // Merge the relevant signals
        textFieldValueSignal = Signal.merge(textFieldValuesSignal, textFieldContinuousValuesSignal, textFieldValuePipe.output)

        // This will print the text field's value when it's changed by the user or programmatically
        textFieldValueSignal.observeValues { value in
            print(value ?? "nil")
        }
    }

    // Use this to change the text field's value programmatically
    func setTextFieldText(_ text: String?) {
        textFieldValuePipe.input.send(value: text)
    }

}

Answer 3

要收听文本属性中的程序更改：

let textField = UITextField()
let signal = textField.reactive.signal(forKeyPath: #keyPath(UITextField.text)).map { $0 as? String }
signal.observeValues { print($0) }
textField.text = "Hello World"

请注意，如果您想观察由于用户操作引起的更改，您仍需要观察continuousTextValues。

Answer 4

您可以使用rac_textSignal属性监听textFields。

[self.someTextField.rac_textSignal subscribeNext:^(NSString* text) {       
     NSLog(@"%@", text); 
}];

每次textField文本更改时，都会调用此闭包。