在后台

Question

使用iOS发件人API框架，当我的应用程序在后台运行时，SDK会撕毁所有的连接，在应用程序被放回前台之前，我不能再启动任何媒体。我的应用程序播放音频，允许在后台运行和流。有没有办法告诉Googlecast的框架让套接字保持打开？

下面是背靠背的日志：

信息:将辞职活跃

信息:现在是背景

精细：-GCKCastSocket断开连接

罚款：-GCKCastSocket doTeardownWithError: doTeardownWithError

罚款：-GCKCastSocket doTeardownWithError:通知委托套接字已断开

好的：-GCKHeartbeatChannel didDisconnect断开-如果需要的话停止心跳定时器

罚款：-GCKCastSocket套接字socketDidDisconnect:withError: socketDidDisconnect:withError："(null)“

然后，当应用程序恢复: INFO:进入前台时

罚款：-GCKCastSocket doTeardownWithError: doTeardownWithError

罚款：-GCKCastSocket doTeardownWithError:通知委托套接字已断开

-GCKCastSocket connectToHost:端口:withTimeout:连接到端口8009l上的"192.168.1.4“

信息:变得活跃了

罚款：-GCKCastSocket套接字:didConnectToHost:端口: socketDidConnect：

罚款：-GCKCastSocket socketDidSecure: socketDidSecure：

罚款：-GCKCastSocket套接字:didReadData:withTag:前缀读取，预期消息length=1307

罚款：-GCKDeviceAuthChannel didReceiveBinaryMessage:正版Google设备didDeviceAuthenticated=YES

精细：-GCKDeviceManager deviceAuthChannelDidAuthenticate:正宗设备，连接接收通道

罚款：-GCKCastSocket套接字:didReadData:withTag:前缀读取，预期消息length=474

精细:可用receiverControlChannel:didReceiveStatusForApplication:应用程序连接(CC1AD845)

connectAndNotifyDidConnectToApplication:launchedApplication:连接到应用程序<0x1467c8f0:GCKApplicationMetadata>默认媒体接收器(CC1AD845)，传输ID web-11

罚款：-GCKCastSocket套接字:didReadData:withTag:前缀读取，预期消息length=135

罚款：-GCKMediaControlChannel didReceiveTextMessage:消息接收：{“类型”：“MEDIA_STATUS”，“状态”：[]，"requestId":6}

Answer 1

使用iOS发件人API的2.0版本，GCKCastSocket在接收到UIApplicationDidEnterBackgroundNotification时关闭，这不是可以配置的东西。

这意味着：

• 当应用程序处于后台时，不能将新媒体从应用程序推送到chromecast
• 不可能实现锁屏幕控件。

备选方案(仅限自定义接收方)：

• 向接收者发送要播放的媒体列表
• 从云端直接从接收器获取新媒体

有关更多细节，请参见this question或this one。

Answer 2

这是我用于其他需要的解决方案，但我想它也可以在这里应用(还没有测试)。

1.将后台任务处理程序创建为dispatch_block_t，例如

 dispatch_block_t myDummyBackgroundTaskBlock = {
    [[UIApplication sharedApplication] endBackgroundTask:myDummyBackgroundTask];
    myDummyBackgroundTask = UIBackgroundTaskInvalid;
    myDummyBackgroundTask = [app beginBackgroundTaskWithExpirationHandler:myDummyBackgroundTask];
};

2.在某个地方定义这个背景和前台任务处理程序

    // foreground
    -(void)handleTasksForApplicationInForeground {
    if(myDummyBackgroundTask) { // reset that task
       [[UIApplication sharedApplication] endBackgroundTask: myDummyBackgroundTask];
       myDummyBackgroundTask = UIBackgroundTaskInvalid;
     }
    }

     // background
     -(void) handleTasksForApplicationInBackground {
         UIDevice *device = [UIDevice currentDevice];
         BOOL backgroundSupported = NO;
        if ([device respondsToSelector:@selector(isMultitaskingSupported)])
         backgroundSupported = device.multitaskingSupported;
        if(backgroundSupported && backgroundEnabled) { // perform a background task

            myDummyBackgroundTaskBlock = ^{
                [[UIApplication sharedApplication] endBackgroundTask: myDummyBackgroundTaskBlock];
                myDummyBackgroundTaskBlock = UIBackgroundTaskInvalid;
           };

           SEL sel = @selector(doDummyBackgroundTask);
           [self doBackgroundTaskAsync:sel];

           [self performSelector:@selector(doBackgroundTaskAsync:) withObject:nil afterDelay:500.0f]; /// LP: this is the funny part since iOS will kill the task after 500 sec.
             }
           }

1. 现在，让我们在应用程序委托中处理后台模式(正如在应用程序.plist中使用不同选项激活后台模式之前所定义的那样)：

    -(void)applicationDidEnterBackground:(UIApplication *)application {
       [self handleTasksForApplicationInBackground];
     }

    -(void)applicationWillEnterForeground:(UIApplication *)application {
       [self handleTasksForApplicationInForeground];
     }

1. 让我们看看后台异步任务选择器做什么

        -(void) doBackgroundTaskAsync:(SEL)selector {

        @try {
             if( [[UIApplication sharedApplication] backgroundTimeRemaining] < 5 ) { 
               return;
             }

           if(!myDummyBackgroundTaskBlock) { // need to create again on-the-fly
                myDummyBackgroundTaskBlock = ^{
                      [[UIApplication sharedApplication] endBackgroundTask:myDummyBackgroundTask];
                     myDummyBackgroundTask = UIBackgroundTaskInvalid;
                };
             }

            myDummyBackgroundTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:myDummyBackgroundTaskBlock];
          dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{

           while ([[UIApplication sharedApplication] backgroundTimeRemaining] > 5.0) {
              int delta = 5.0;
              [self performSelector: selector ];
              sleep(delta);
          }
        });
      }
       @catch (...) {
     }
    }