Swift：将参数传递给选择器 [英] Swift: Passing a parameter to selector

问题描述

使用Swift 3，Xcode 8.2.1

Using Swift 3, Xcode 8.2.1

方法：

func moveToNextTextField(tag: Int) {
   print(tag)
}

下面的行编译正常，但标记有一个未初始化的值：

The lines below compile fine, but tag has an uninitialized value:

let selector = #selector(moveToNextTextField)
Timer.scheduledTimer(timeInterval: 0.2, target: self, selector: selector, userInfo: nil, repeats: false)

但是，我需要传递一个参数。下面无法编译：

However, I need to pass a parameter. Below fails to compile:

let selector = #selector(moveToNextTextField(tag: 2))

Swift Compile Error:
Argument of #selector does not refer to an @objc method, property, or initializer.

如何将参数传递给选择器？

How can I pass an argument to a selector?

推荐答案

#selector 仅描述方法签名。在你的情况下，初始化选择器的正确方法是

#selector describes method signature only. In your case the correct way to initialize the selector is

let selector = #selector(moveToNextTextField(tag:))

Timer具有共同的目标 - 动作机制。 Target通常是self，action是一个带有一个参数 sender：Timer 的方法。您应该将其他数据保存到 userInfo 字典，并从方法中的 sender 参数中提取它：

Timer has the common target-action mechanism. Target is usually self and action is a method that takes one parameter sender: Timer. You should save additional data to userInfo dictionary, and extract it from sender parameter in the method:

func moveToNextTextField(sender: Timer) {
   print(sender.userInfo?["tag"])
}
...
let selector = #selector(moveToNextTextField(sender:))
Timer.scheduledTimer(timeInterval: 0.2, target: self, selector: selector, userInfo: ["tag": 2], repeats: false)

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