我试图在Swift中创建一个NSTimer,但我遇到了一些麻烦。

NSTimer(timeInterval: 1, target: self, selector: test(), userInfo: nil, repeats: true)

Test()是同一个类中的一个函数。


我在编辑器中得到一个错误:

无法找到一个超载的'init'接受提供的 参数

当我把selector: test()改为selector: nil时,错误就消失了。

我试过了:

选择器:测试() 选择器:测试 选择器:选择器(测试())

但是什么都没用,我在参考文献中找不到解决方案。


当前回答

当使用performSelector()时

/addtarget()/NStimer.scheduledTimerWithInterval()方法你的方法(匹配选择器)应该被标记为

@objc
For Swift 2.0:
    {  
        //...
        self.performSelector(“performMethod”, withObject: nil , afterDelay: 0.5)
        //...


    //...
    btnHome.addTarget(self, action: “buttonPressed:", forControlEvents: UIControlEvents.TouchUpInside)
    //...

    //...
     NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector : “timerMethod”, userInfo: nil, repeats: false)
    //...

}

@objc private func performMethod() {
…
}
@objc private func buttonPressed(sender:UIButton){
….
}
@objc private func timerMethod () {
….
}

对于Swift 2.2, 你需要写“#selector()”而不是字符串和选择器名称,这样拼写错误和崩溃的可能性就不会再存在了。下面是示例

self.performSelector(#selector(MyClass.performMethod), withObject: nil , afterDelay: 0.5)

其他回答

Create Refresh control using Selector method.   
    var refreshCntrl : UIRefreshControl!
    refreshCntrl = UIRefreshControl()
    refreshCntrl.tintColor = UIColor.whiteColor()
    refreshCntrl.attributedTitle = NSAttributedString(string: "Please Wait...")
    refreshCntrl.addTarget(self, action:"refreshControlValueChanged", forControlEvents: UIControlEvents.ValueChanged)
    atableView.addSubview(refreshCntrl)

//刷新控制方法

func refreshControlValueChanged(){
    atableView.reloadData()
    refreshCntrl.endRefreshing()

}

斯威夫特4.0

创建如下所示的选择器。

1.将事件添加到如下按钮:

button.addTarget(self, action: #selector(clickedButton(sender:)), for: UIControlEvents.touchUpInside)

函数如下所示:

@objc func clickedButton(sender: AnyObject) {

}

我发现很多答案都很有用,但我不清楚如何用一个不是按钮的东西来做到这一点。我在swift中添加了一个手势识别器到UILabel中,所以在阅读以上所有内容后,我发现以下是对我有用的:

let tapRecognizer = UITapGestureRecognizer(
            target: self,
            action: "labelTapped:")

其中“Selector”被声明为:

func labelTapped(sender: UILabel) { }

请注意,它是公共的,我没有使用Selector()语法,但也可以这样做。

let tapRecognizer = UITapGestureRecognizer(
            target: self,
            action: Selector("labelTapped:"))

当使用performSelector()时

/addtarget()/NStimer.scheduledTimerWithInterval()方法你的方法(匹配选择器)应该被标记为

@objc
For Swift 2.0:
    {  
        //...
        self.performSelector(“performMethod”, withObject: nil , afterDelay: 0.5)
        //...


    //...
    btnHome.addTarget(self, action: “buttonPressed:", forControlEvents: UIControlEvents.TouchUpInside)
    //...

    //...
     NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector : “timerMethod”, userInfo: nil, repeats: false)
    //...

}

@objc private func performMethod() {
…
}
@objc private func buttonPressed(sender:UIButton){
….
}
@objc private func timerMethod () {
….
}

对于Swift 2.2, 你需要写“#selector()”而不是字符串和选择器名称,这样拼写错误和崩溃的可能性就不会再存在了。下面是示例

self.performSelector(#selector(MyClass.performMethod), withObject: nil , afterDelay: 0.5)

自从Swift 3.0发布以来,它甚至更微妙地声明了一个targetAction合适

class MyCustomView : UIView {

    func addTapGestureRecognizer() {

        // the "_" is important
        let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(MyCustomView.handleTapGesture(_:)))
        tapGestureRecognizer.numberOfTapsRequired = 1
        addGestureRecognizer(tapGestureRecognizer)
    }

    // since Swift 3.0 this "_" in the method implementation is very important to 
    // let the selector understand the targetAction
    func handleTapGesture(_ tapGesture : UITapGestureRecognizer) {

        if tapGesture.state == .ended {
            print("TapGesture detected")
        }
    }
}