检查:

斯威夫特2

var timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: Selector("update"), userInfo: nil, repeats: true)

斯威夫特，3,4,5

var timer = Timer.scheduledTimer(timeInterval: 0.01, target: self, selector: #selector(self.update), userInfo: nil, repeats: true)

你需要在Swift 3中使用Timer而不是NSTimer。

这里有一个例子:

Timer.scheduledTimer(timeInterval: 1, 
    target: self, 
    selector: #selector(YourController.update), 
    userInfo: nil, 
    repeats: true)

// @objc selector expected for Timer
@objc func update() {
    // do what should happen when timer triggers an event
}

Swift 3, pre iOS 10

func schedule() {
    DispatchQueue.main.async {
      self.timer = Timer.scheduledTimer(timeInterval: 20, target: self,
                                   selector: #selector(self.timerDidFire(timer:)), userInfo: nil, repeats: false)
    }
  }

  @objc private func timerDidFire(timer: Timer) {
    print(timer)
  }

Swift 3, iOS 10+

DispatchQueue.main.async {
      self.timer = Timer.scheduledTimer(withTimeInterval: 20, repeats: false) { timer in
        print(timer)
      }
    }

笔记

它需要在主队列上 回调函数可以是public, private，… 回调函数需要@objc

首先声明你的计时器

var timer: Timer?

然后在viewDidLoad()或任何你想要启动计时器的函数中添加line

timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(action), userInfo: nil, repeats: false)

这是func，你将回调它来做一些事情它必须是@objc

@objc func action () {
print("done")
}

如果你init定时器的方法

let timer = Timer(timeInterval: 3, target: self, selector: #selector(update(_:)), userInfo: [key : value], repeats: false)

func update(_ timer : Timer) {

}

然后将它添加到循环中，使用方法other selector将不会被调用

RunLoop.main.add(timer!, forMode: .defaultRunLoopMode)

注意:如果你想要这个重复，使重复为真，并保持定时器的引用，否则更新方法将不会被调用。

如果你使用这种方法。

Timer.scheduledTimer(timeInterval: seconds, target: self, selector: #selector(update(_:)), userInfo: nil, repeats: true)

如果repeat为真，则保留一个参考供以后使用。

swift 3和Xcode 8.2 (有块很好，但如果你编译为iOS9和想要userInfo):

...

        self.timer = Timer(fireAt: fire,
                           interval: deltaT,
                           target: self,
                           selector: #selector(timerCallBack(timer:)),
                           userInfo: ["custom":"data"],
                           repeats: true)

        RunLoop.main.add(self.timer!, forMode: RunLoopMode.commonModes)
        self.timer!.fire()
}

func timerCallBack(timer: Timer!){
        let info = timer.userInfo
        print(info)
    }