Google Chromecast SDK TearDown in background

Question

Using the iOS Sender API Framework, when my application goes in the background, the SDK tears down all connections and I cannot launch any more media until the app is put ba

Answer 1

With the version 2.0 of the iOS Sender API, the GCKCastSocket is closed upon receiving a UIApplicationDidEnterBackgroundNotification and this is not something that can be configured.

That means:

• no new media can be pushed from the app to the chromecast while the app is in the background
• it is not possible to implement lock screen controls

Alternatives (custom receiver only):

• Send a list of media to be played to the receiver
• Fetch new media from the cloud directly from the receiver

See also this question or this one for more details.

Answer 2

This is a solution I used for other needs, but I guess it could be applied here as well (not tested yet)

1. Create a background task handlers as dispatch_block_t, let's say

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

2. Define somewhere this background and foreground tasks handler

    // 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.
             }
           }

3. Now let's handle in the application delegate the background mode (As defined before you can activate background mode with different options in your app .plist):

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

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

4. Let's see what the background async task selector does

        -(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 (...) {
     }
    }