Question

想象一下，您正在使用应用，然后按主页按钮。该应用已在运行，但您无法看到。然后再次按下应用程序图标，将应用程序恢复到正面。

代码中调用了什么？在ViewController中调用什么？

Answer 1

    //In appDelegate class following delegate method called when you hit home button
     func applicationWillResignActive(application: UIApplication)
        {

        }
        // this EnterBackground delegate is called
        func applicationDidEnterBackground(application: UIApplication)
        {

        }

     //When you tap on app icon again following 2 delegate methods called
   func applicationWillEnterForeground(application: UIApplication)
    {

    }
        //finally when your app become active
        func applicationDidBecomeActive(application: UIApplication)
        {

        }

    //This called when app terminates
       func applicationWillTerminate(application: UIApplication)
        {

        }

    This is called life cycle of app.

Answer 2

你有一个名为AppDelegate.swift的文件。在那里你可以找到默认的5种方法。

正如您所看到的，在调用函数时已有一个很好的描述：

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]!) -> Bool {
    //Called if the app is started
          return true
}


func applicationWillResignActive(application: UIApplication) {
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

func applicationDidEnterBackground(application: UIApplication) {
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

func applicationWillEnterForeground(application: UIApplication) {
    // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}

func applicationDidBecomeActive(application: UIApplication) {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

func applicationWillTerminate(application: UIApplication) {

    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    // Saves changes in the application's managed object context before the application terminates.
}

当我从主屏幕按下图标但它已经在运行时，应用程序会发生什么？

2 个答案: