Adding a Single Task to a Queue

The following example shows how to use the block-based variants for dispatching tasks asynchronously and synchronously: 

dispatch_queue_t myCustomQueue;
myCustomQueue = dispatch_queue_create("com.example.MyCustomQueue", NULL);
dispatch_async(myCustomQueue, ^{
    printf("Do some work here.\n");
});
printf("The first block may or may not have run.\n");
dispatch_sync(myCustomQueue, ^{
    printf("Do some more work here.\n");
});
printf("Both blocks have completed.\n");