在 Swift 中将参数传递给选择器 [英] Passing arguments to selector in Swift

问题描述

我正在以编程方式将 UITapGestureRecognizer 添加到我的一个视图中:

I'm programmatically adding a UITapGestureRecognizer to one of my views:

let gesture = UITapGestureRecognizer(target: self, action: #selector(self.handleTap(modelObj:myModelObj)))

self.imageView.addGestureRecognizer(gesture)

func handleTap(modelObj: Model) {
  // Doing stuff with model object here
}

我遇到的第一个问题是'#selector' 的参数没有引用 '@Objc' 方法、属性或初始化程序.

The first problem I encountered was "Argument of '#selector' does not refer to an '@Objc' method, property, or initializer.

酷，所以我在 handleTap 签名中添加了@objc:

Cool, so I added @objc to the handleTap signature:

@objc func handleTap(modelObj: Model) {
  // Doing stuff with model object here
}

现在我收到错误方法无法标记为@objc，因为参数的类型无法在 Objective-C 中表示.

Now I'm getting the error "Method cannot be marked @objc because the type of the parameter cannot be represented in Objective-C.

这只是建筑物地图的图像，其中一些图钉图像指示了兴趣点的位置.当用户点击其中一个引脚时，我想知道他们点击了哪个兴趣点，并且我有一个描述这些兴趣点的模型对象.我使用此模型对象为图钉图像提供地图上的坐标，因此我认为将对象发送到手势处理程序对我来说很容易.

It's just an image of the map of a building, with some pin images indicating the location of points of interest. When the user taps one of these pins I'd like to know which point of interest they tapped, and I have a model object which describes these points of interest. I use this model object to give the pin image it's coordinates on the map so I thought it would have been easy for me to just send the object to the gesture handler.

推荐答案

看来你误解了几件事.

当使用 目标/动作，函数签名必须有一定的形式……

When using target/action, the function signature has to have a certain form…

func doSomething()

或

func doSomething(sender: Any)

或

func doSomething(sender: Any, forEvent event: UIEvent)

在哪里……

sender参数是发送动作消息的控制对象.

The sender parameter is the control object sending the action message.

在您的情况下，发件人是 UITapGestureRecognizer

In your case, the sender is the UITapGestureRecognizer

另外，#selector() 应该包含 func 签名，并且不包含传递的参数.所以对于……

Also, #selector() should contain the func signature, and does NOT include passed parameters. So for…

func handleTap(sender: UIGestureRecognizer) {
    
}

你应该……

let gesture = UITapGestureRecognizer(target: self, action: #selector(handleTap(sender:)))

假设func和手势在一个视图控制器中，其中modelObj是一个属性/ivar，不需要通过手势识别器传递，你可以在<代码>handleTap

Assuming the func and the gesture are within a view controller, of which modelObj is a property / ivar, there's no need to pass it with the gesture recogniser, you can just refer to it in handleTap

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