我试着
var timer = NSTimer()
timer(timeInterval: 0.01, target: self, selector: update, userInfo: nil, repeats: false)
但是,我得到了一个错误
'(timeInterval: $T1, target: ViewController, selector: () -> (), userInfo: NilType, repeats: Bool) -> $T6' is not identical to 'NSTimer'
这是可行的:
override func viewDidLoad() {
super.viewDidLoad()
// Swift block syntax (iOS 10+)
let timer = Timer(timeInterval: 0.4, repeats: true) { _ in print("Done!") }
// Swift >=3 selector syntax
let timer = Timer.scheduledTimer(timeInterval: 0.4, target: self, selector: #selector(self.update), userInfo: nil, repeats: true)
// Swift 2.2 selector syntax
let timer = NSTimer.scheduledTimerWithTimeInterval(0.4, target: self, selector: #selector(MyClass.update), userInfo: nil, repeats: true)
// Swift <2.2 selector syntax
let timer = NSTimer.scheduledTimerWithTimeInterval(0.4, target: self, selector: "update", userInfo: nil, repeats: true)
}
// must be internal or public.
@objc func update() {
// Something cool
}
对于Swift 4,你想要获取选择器的方法必须暴露在Objective-C中,因此@objc属性必须添加到方法声明中。
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
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。
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")
}