我们可以在应用程序已最小化后调用该方法吗？ [英] Can we call the method after the application has been minimized?

问题描述

iOS

我们可以在应用程式最小化后调用方法吗？

秒后调用 applicationDidEnterBackground：。

我使用这个代码，但 code>方法不调用

   - （void）test 
 {
 printf Test called！）; 
} 
 
  - （void）applicationDidEnterBackground：（UIApplication *）application 
 {
 [self performSelector：@selector（test）withObject：nil afterDelay：5.0]; 
} 
  

解决方案

在你背景之后调用方法的API（只要你的任务不需要太长时间 - 通常〜10分钟是最大允许时间）。

iOS不会让应用程序在后台运行时触发计时器，所以我发现在应用程序背景之前分派后台线程，然后使该线程进入休眠状态，与计时器的效果相同。

将以下代码放在应用程序代理的 - （void）applicationWillResignActive：（UIApplication *）application 方法中：

  //分派到后台队列
 dispatch_async（dispatch_get_global_queue（DISPATCH_QUEUE_PRIORITY_BACKGROUND，0），^ {
 
 // Tell您要启动后台任务的系统
 UIBackgroundTaskIdentifier taskID = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler：^ {
 //系统清除应用程序之前清除
}]; 
 
 //睡眠块5秒
 [NSThread sleepForTimeInterval：5.0]; 
 
 //如果应用程序是后台的（而不是非活动的）调用方法
 if（application.applicationState == UIApplicationStateBackground）
 [self performSelector：@selector（test） ]; //或者，你可以调用[self test]; here 
 
 //告诉系统任务已经结束。 
 if（taskID！= UIBackgroundTaskInvalid）{
 [[UIApplication sharedApplication] endBackgroundTask：taskID]; 
} 
 
}）; 
  

iOS

Can we call the method after the application has been minimized?

For example, 5 seconds after was called applicationDidEnterBackground:.

I use this code, but test method don't call

- (void)test
{
    printf("Test called!");
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    [self performSelector:@selector(test) withObject:nil afterDelay:5.0];
}

解决方案

You can use the background task APIs to call a method after you've been backgrounded (as long as your task doesn't take too long - usually ~10 mins is the max allowed time).

iOS doesn't let timers fire when the app is backgrounded, so I've found that dispatching a background thread before the app is backgrounded, then putting that thread to sleep, has the same effect as a timer.

Put the following code in your app delegate's - (void)applicationWillResignActive:(UIApplication *)application method:

// Dispatch to a background queue
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{

    // Tell the system that you want to start a background task
    UIBackgroundTaskIdentifier taskID = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
        // Cleanup before system kills the app
    }];

    // Sleep the block for 5 seconds
    [NSThread sleepForTimeInterval:5.0];

    // Call the method if the app is backgrounded (and not just inactive)
    if (application.applicationState == UIApplicationStateBackground)
        [self performSelector:@selector(test)];  // Or, you could just call [self test]; here

    // Tell the system that the task has ended.
    if (taskID != UIBackgroundTaskInvalid) {
        [[UIApplication sharedApplication] endBackgroundTask:taskID];
    }

});

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