如何当用户返回到后台程序触发功能？ [英] How to trigger a function when a user goes back to a background app?

问题描述

例如，一个用户打开一个应用程序，presses home键，然后回来到应用程序一次。

For example, an user opens an app, presses the home button, and then comes back to the app again.

有什么办法来触发某些功能，当用户返回到应用程序？如汽车当用户返回到应用程序加载的视图对象。

Is there any way to trigger certain functions when the user navigates back to the app? Such as auto load a view object when the user is back to the app.

这问题是为Android和放大器; iOS版。

This question is for both Android & iOS.

推荐答案

使用以下到您的喜好在项目的 AppDelegate.m 文件（仅适用于iOS）

Use the following to your likings in the projects's AppDelegate.m file (iOS only)

 - (void)applicationWillResignActive:(UIApplication *)application
    {
        // 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.
    }

    - (void)applicationDidEnterBackground:(UIApplication *)application
    {
        // 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.
    }

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

    - (void)applicationDidBecomeActive:(UIApplication *)application
    {
        // 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.
    }

    - (void)applicationWillTerminate:(UIApplication *)application
    {
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    }

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