beginBackgroundTaskWithExpirationHandler [英] beginBackgroundTaskWithExpirationHandler

问题描述

我正在做一个应用程序，音频将在后台播放。在下面的代码中，bgTask是未声明的。 bgTask是什么类型的对象？

I am making an application where audio will play in the background. In the following code, bgTask is undeclared. What kind of object should bgTask be?

- (void)applicationDidEnterBackground:(UIApplication *)application 
{
    UIApplication  *app = [UIApplication sharedApplication];
    bgTask = [app beginBackgroundTaskWithExpirationHandler:^{ 
        [app endBackgroundTask:bgTask]; 
        bgTask = UIBackgroundTaskInvalid;
    }];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{});

    [app endBackgroundTask:bgTask]; 
    bgTask = UIBackgroundTaskInvalid;
}

推荐答案

您需要声明bgTask您分配：

You need to declare bgTask before you assign:

UIBackgroundTaskIdentifier bgTask = 0;

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