类 Y 的对象 X 没有在 Swift 中实现 methodSignatureForSelector

问题描述

我有一个类 Person 被多次实例化.每个人都有自己的计时器.在 Person 的 init 中，我调用 startTimer().

I have a class Person which is instantiated multiple times.Each person get's their own timer. Upon in my init for Person I call startTimer().

class Person {
 var timer = NSTimer()
 func startTimer() {
    timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("timerTick"), userInfo: nil, repeats: true)
 }

 func timerTick() {
    angerLevel++
    println("Angry! (angerLevel)")
 }
...
...
}

所以我可能在 Person[] 数组中有 3 个 Person 实例.我收到一个错误:

So I may have 3 instances of Person in an array of Person[]. I am getting an error:

2014-06-25 13:57:14.956 ThisProgram[3842:148856] *** NSForwarding: warning: object 0x113760048 of class '_TtC11ThisProgram6Person' does not implement methodSignatureForSelector: -- trouble ahead

我在别处读到我应该从 NSObject 继承，但这是在 Swift 中而不是在 Obj-C 中.该功能在课堂上，所以我不知道该怎么做.

I read elsewhere that I should inherit from NSObject but this is in Swift not Obj-C. The function is within the class so I am not sure what to do.

推荐答案

不要把 NSObject 看作一个 Objective-C 的类，把它看作 Cocoa/Foundation 类.即使您使用的是 Swift 而不是 Objective-C，您仍然使用的是所有相同的框架.

Don't think of NSObject as an Objective-C class, think of it as a Cocoa/Foundation class. Even though you're using Swift instead of Objective-C, you're still using all the same frameworks.

两种选择:(1)将 dynamic 属性添加到要作为选择器引用的函数中:

Two options: (1) add the dynamic attribute to the function you want to reference as a selector:

    dynamic func timerTick() {
        self.angerLevel++
        print("Angry! (self.angerLevel)")
    }

或者 (2) 将 Person 声明为 NSObject 的子类，然后在初始化程序的开头调用 super.init():

Or (2) declare Person as a subclass of NSObject, then just call super.init() at the beginning of your initializer:

class Person: NSObject {
    var timer = NSTimer()
    var angerLevel = 0

    func startTimer() {
        print("starting timer")
        timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: "timerTick", userInfo: nil, repeats: true)
    }

    func timerTick() {
        self.angerLevel++
        print("Angry! (self.angerLevel)")
    }

    override init() {
        super.init()
        self.startTimer()
    }
}

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