在Swift中，如何检测哪个UIControlEvents触发了该动作? [英] In Swift, how do you detect which UIControlEvents triggered the action?

问题描述

我目前有4个UITextField的

I currently have 4 UITextField's

@IBOutlet weak var fNameTextField: UITextField!
@IBOutlet weak var lNameTextField: UITextField!
@IBOutlet weak var emailTextField: UITextField!
@IBOutlet weak var phoneTextField: UITextField!

我想跟踪他们的各种事件:

and I want to keep track of their various events:

[UIControlEvents.EditingChanged, UIControlEvents.EditingDidBegin, UIControlEvents.EditingDidEnd ]

但是我不想有3个单独的事件处理程序，所以我创建了一个这样的函数.该函数可以很好地告诉我哪个UITextField触发了一个事件，但没有告诉我触发了哪个事件.

but I don't want to have 3 event separate event handlers so I created a single function like this. This function does a great job of telling me which UITextField fired an event but it doesn't tell me which event was triggered.:

fNameTextField.addTarget(self, action: "onChangeTextField:", forControlEvents: UIControlEvents.AllTouchEvents)
lNameTextField.addTarget(self, action: "onChangeTextField:", forControlEvents: UIControlEvents.AllTouchEvents)
emailTextField.addTarget(self, action: "onChangeTextField:", forControlEvents: UIControlEvents.AllTouchEvents)
phoneTextField.addTarget(self, action: "onChangeTextField:", forControlEvents: UIControlEvents.AllTouchEvents)

func onChangeTextField(sender:UITextField){
    switch(sender){
        case fNameTextField:
            print("First Name")
        case lNameTextField:
            print("Last Name")
        case emailTextField:
            print("E-mail")
        case phoneTextField:
            print("Phone")
        default: break
    }
}

如何打印发件人的姓名和触发的事件的名称(例如:.EditingDidEnd，.EditingDidEnd，.EditingDidEnd)?

How can I print both the name of the sender and the name of the event triggered (ex: .EditingDidEnd, .EditingDidEnd, .EditingDidEnd)?

理想情况下，我不想编写多个事件处理程序，我希望使用一个函数.

Ideally, I do not want to write multiple event handlers, I'd prefer a single function.

类似这样的东西:

func onChangeTextField(sender:UITextField){
    switch(sender.eventTriggerd){
        case UIControlEvents.EditingChanged:
            println("EditingChanged")
        case UIControlEvents.EditingDidBegin:
            println("EditingDidBegin")
        case UIControlEvents.EditingDidEnd:
            println("EditingDidEnd")
        default: break
    }
}

推荐答案

不幸的是，您无法区分是哪个控制事件触发了动作处理程序.这与Swift无关.这只是可可的功能.

Unfortunately, you cannot distinguish what control event triggered an action handler. This has nothing to do with Swift; it's just a feature of Cocoa.

这是一个奇怪的设计决定，但事实就是如此.参见例如我的书，它对此抱怨:

It's a strange design decision, but that's just how it is. See, for example, my book, which complains about it:

奇怪的是，没有一个动作选择器参数提供任何方法来了解哪个控制事件触发了当前的动作选择器调用！因此，例如，要将内部向上触摸"控制事件与外部向上触摸"控制事件区分开，它们对应的目标-操作对必须指定两个不同的操作处理程序；如果将它们分派到同一操作处理程序，则该处理程序将无法发现发生了哪个控制事件.

Curiously, none of the action selector parameters provide any way to learn which control event triggered the current action selector call! Thus, for example, to distinguish a Touch Up Inside control event from a Touch Up Outside control event, their corresponding target–action pairs must specify two different action handlers; if you dispatch them to the same action handler, that handler cannot discover which control event occurred.

这篇关于在Swift中，如何检测哪个UIControlEvents触发了该动作?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！