Swift 3 - 如何让计时器在后台工作

在Swift中，计时器是一种常用的功能，可以用来执行定时任务或者实现一些延迟操作。然而，默认情况下，当我们的应用程序进入后台时，计时器会被暂停，这可能会导致我们的应用无法在后台持续进行一些操作。那么，如何让计时器在后台工作呢？本文将为大家介绍一种实现计时器在后台工作的方法，并提供相应的案例代码。

swift
import Foundation
class TimerManager {
    static let shared = TimerManager()
    
    private var timer: Timer?
    
    func startTimer() {
        timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(handleTimer), userInfo: nil, repeats: true)
        RunLoop.current.add(timer!, forMode: .common)
    }
    
    func stopTimer() {
        timer?.invalidate()
        timer = nil
    }
    
    @objc private func handleTimer() {
        print("Timer fired!")
    }
}

swift
import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }
    
    func applicationDidEnterBackground(_ application: UIApplication) {
        TimerManager.shared.startTimer()
    }
    
    func applicationWillEnterForeground(_ application: UIApplication) {
        TimerManager.shared.stopTimer()
    }
}