我试过了
var timer = NSTimer()
timer(timeInterval: 0.01, target: self, selector: update, userInfo: nil, repeats: false)
但是，我说错了
'(timeInterval: $T1, target: ViewController, selector: () -> (), userInfo: NilType, repeats: Bool) -> $T6' is not identical to 'NSTimer'
这将有效：
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，您希望获取选择器的方法必须暴露给Objective-C，因此必须将@objc属性添加到方法声明中。
在Swift 3中，与@objc类似：
func startTimerForResendingCode() {
let timerIntervalForResendingCode = TimeInterval(60)
Timer.scheduledTimer(timeInterval: timerIntervalForResendingCode,
target: self,
selector: #selector(timerEndedUp),
userInfo: nil,
repeats: false)
}
@objc func timerEndedUp() {
output?.timerHasFinishedAndCodeMayBeResended()
}
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(createEnemy), userInfo: nil, repeats: true)
并通过名称createEnemy创建乐趣
fund createEnemy ()
{
do anything ////
}
如果你初始化计时器的方法
let timer = Timer(timeInterval: 3, target: self, selector: #selector(update(_:)), userInfo: [key : value], repeats: false)
func update(_ timer : Timer) {
}
然后使用方法将其添加到循环中，不会调用其他选择器
RunLoop.main.add(timer!, forMode: .defaultRunLoopMode)
注意：如果您希望重复生成重复，并保留定时器的引用，否则将不会调用更新方法。
如果您使用此方法。
Timer.scheduledTimer(timeInterval: seconds, target: self, selector: #selector(update(_:)), userInfo: nil, repeats: true)
如果重复为真，请保留一个参考供以后使用。
NSTimer已在Swift 4.2中重命名为Timer。这个语法适用于4.2：
let timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(UIMenuController.update), userInfo: nil, repeats: true)
您可以使用计时器多次执行操作，如以下示例所示。计时器调用一种方法每半秒更新一次标签。
这是代码：
import UIKit
class ViewController: UIViewController {
var counter = 0
var timer = Timer()
@IBOutlet weak var label: UILabel!
// start timer
@IBAction func startTimerButtonTapped(sender: UIButton) {
timer.invalidate() // just in case this button is tapped multiple times
// start the timer
timer = Timer.scheduledTimer(timeInterval: 0.5, target: self, selector: #selector(timerAction), userInfo: nil, repeats: true)
}
// stop timer
@IBAction func cancelTimerButtonTapped(sender: UIButton) {
timer.invalidate()
}
// called every time interval from the timer
func timerAction() {
counter += 1
label.text = "\(counter)"
}
}
您还可以使用计时器在将来的某个时间安排一次性事件。与上述示例的主要区别在于您使用repeats: false而不是true。
timer = Timer.scheduledTimer(timeInterval: 2.0, target: self, selector: #selector(delayedAction), userInfo: nil, repeats: false)
上面的示例在设置计时器两秒后调用名为delayedAction的方法。它不会重复，但如果您需要在事件发生之前取消该事件，您仍然可以调用timer.invalidate()。
更新到Swift 4，利用userInfo：
class TimerSample {
var timer: Timer?
func startTimer() {
timer = Timer.scheduledTimer(timeInterval: 5.0,
target: self,
selector: #selector(eventWith(timer:)),
userInfo: [ "foo" : "bar" ],
repeats: true)
}
// Timer expects @objc selector
@objc func eventWith(timer: Timer!) {
let info = timer.userInfo as Any
print(info)
}
}
从iOS 10开始，还有一个新的基于块的Timer工厂方法，它比使用选择器更清晰：
_ = Timer.scheduledTimer(withTimeInterval: 5, repeats: false) { timer in
label.isHidden = true
}
Swift 3，iOS 10之前
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
@objc检查：
var timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: Selector("update"), userInfo: nil, repeats: true);
你需要在Swift 3中使用Timer而不是NSTimer。
这是一个例子：
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
}
对于swift 3和Xcode 8.2（很高兴有块，但如果你为iOS9编译并想要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)
}
这是swift中的一个简单的计时器类，使您能够：
SimpleTimer(interval: 3,repeats: true){print("tick")}.start()//Ticks every 3 secs
class SimpleTimer {/*<--was named Timer, but since swift 3, NSTimer is now Timer*/
typealias Tick = ()->Void
var timer:Timer?
var interval:TimeInterval /*in seconds*/
var repeats:Bool
var tick:Tick
init( interval:TimeInterval, repeats:Bool = false, onTick:@escaping Tick){
self.interval = interval
self.repeats = repeats
self.tick = onTick
}
func start(){
timer = Timer.scheduledTimer(timeInterval: interval, target: self, selector: #selector(update), userInfo: nil, repeats: true)//swift 3 upgrade
}
func stop(){
if(timer != nil){timer!.invalidate()}
}
/**
* This method must be in the public or scope
*/
@objc func update() {
tick()
}
}