023_swift_定时器

 使用app项目  编译如下代码

//延时1s 输出
        let time=Timer(timeInterval:  1.0, repeats: false) { (timer) in
            print("Timer in a block.")
        }
        time.fire()
            //延时1s 循环输出
        Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { (timer) in
            print("scheduledTimer in a block")
        }

//
//  ViewController.swift
//  DemoApp
//
//  Created by liuan on 2020/4/23.
//  Copyright © 2020 anguo.com. All rights reserved.
//

import UIKit

class ViewController: UIViewController {
var appleCount=0
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.

            //延时1s 循环输出
        Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(ViewController.timerAction(_:)), userInfo: "an apple", repeats: true)
        
    }
    
    @objc func timerAction(_ timer:Timer){
        if self.appleCount==3{
            //停止计时器
            timer.invalidate()
            return
        }
        let parameter=timer.userInfo
        print("I'm eating \(parameter!).")
        self.appleCount+=1
    }

}