NSTimer 与 CACurrentMediaTime()

使用NSTimer和CACurrentMediaTime()来进行时间管理

swift
import UIKit
class ViewController: UIViewController {
    var timer: Timer!
    var count = 0
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(updateTimer), userInfo: nil, repeats: true)
    }
    
    @objc func updateTimer() {
        count += 1
        print("定时器执行了\(count)次")
    }
}

swift
import UIKit
import QuartzCore
class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let startTime = CACurrentMediaTime()
        
        // 需要计时的代码
        
        let endTime = CACurrentMediaTime()
        let elapsedTime = endTime - startTime
        
        print("代码执行时间：\(elapsedTime)秒")
    }
}

swift
import UIKit
import QuartzCore
class ViewController: UIViewController {
    var timer: Timer!
    var startTime: CFTimeInterval!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        startTime = CACurrentMediaTime()
        
        timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(updateTimer), userInfo: nil, repeats: true)
    }
    
    @objc func updateTimer() {
        let currentTime = CACurrentMediaTime()
        let elapsedTime = currentTime - startTime
        let remainingTime = 10 - elapsedTime
        
        if remainingTime > 0 {
            print("倒计时：\(remainingTime)秒")
        } else {
            timer.invalidate()
            print("倒计时结束")
        }
    }
}