import UIKit
class FourVC: UIViewController {
var label:UILabel = UILabel()
var index : Int =
var timer:Timer = Timer()
override func viewDidLoad() {
super.viewDidLoad()
label = UILabel.init()
label.frame = CGRect.init(x:,y:,width: ,height:)
label.text = "计时器"
label.textColor = UIColor.black
self.view.addSubview(label)
timer = Timer.scheduledTimer(timeInterval: , target: self, selector: #selector(createTimer), userInfo: nil, repeats: true)
RunLoop.current.add(timer, forMode: RunLoopMode.commonModes)
timer.fireDate = NSDate.distantFuture
let endTimeBtn : UIButton = UIButton()
endTimeBtn.frame = CGRect.init(x:,y:,width: ,height:)
endTimeBtn.backgroundColor = UIColor.cyan
endTimeBtn.setTitle("停止计时", for: UIControlState.normal)
endTimeBtn.titleColor(for: UIControlState.normal)
endTimeBtn.setTitleColor(UIColor.black, for: UIControlState.normal)
endTimeBtn.addTarget(self, action: #selector(pressBtn1), for: UIControlEvents.touchUpInside)
self.view.addSubview(endTimeBtn)
let startTimeBtn : UIButton = UIButton()
startTimeBtn.frame = CGRect.init(x:,y:,width: ,height:)
startTimeBtn.backgroundColor = UIColor.cyan
startTimeBtn.setTitle("开始计时", for: UIControlState.normal)
startTimeBtn.titleColor(for: UIControlState.normal)
startTimeBtn.setTitleColor(UIColor.black, for: UIControlState.normal)
startTimeBtn.addTarget(self, action: #selector(pressBtn), for: UIControlEvents.touchUpInside)
self.view.addSubview(startTimeBtn)
}
func pressBtn(){
//开始计时，很远的过去
timer.fireDate = NSDate.distantPast
}
func pressBtn1(){
//关闭计时，很远的将来
timer.fireDate = NSDate.distantFuture
}
func createTimer(){
index +=
label.text = "\(index)"
if index == {
//关闭计时器
timer.fireDate = NSDate.distantFuture
label.text = "倒计时停止\(index)"
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}