app额外后台运行操作

//在视图中运行操作中进行周期操作

- (void)applicationDidEnterBackground:(UIApplication *)application

{

[self beingBackgroundUpdateTask];

 

[self endBackgroundUpdateTask];

}

 

 

- (void)beginBackgroundUpdateTask{

    self.backgroundUpdateTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{

        ///在多于5s中做的清理工作

        [self endBackgroundUpdateTask];

    }];

}

- (void)endBackgroundUpdateTask{

    [[UIApplication sharedApplication] endBackgroundTask:self.backgroundUpdateTask];

    self.backgroundUpdateTask = UIBackgroundTaskInvalid;

}