libdispatch: blocks on main queue does not execute

[Lundberg, Johannes]

Hi

I'm a big fan of dispatch and blocks. For iOS development I often use the pattern

dispatch_async(dispatch_get_global_queue(0,0), ^{

  // do some time consuming task

  dispatch_async(dispatch_get_main_queue(), ^{

    // update ui

  });
});

However, this does not work on GNUstep/FreeBSD.

Blocks put on global queues execute fine. Blocks on main queue does not execute.

Not even

  dispatch_async(dispatch_get_main_queue(), ^{

    NSLog(@"Test..");

  });

from main thread/queue works.

Reading the documentation there seem to be a

dispatch_main()
call required to execute blocks on main queue.

If I add this call after the above the blocks on the main queue executes just fine, however, the code freezes there.

As it says:
* This function "parks" the main thread and waits for blocks to be submitted
 * to the main queue. This function never returns.
 * Applications that call NSApplicationMain() or CFRunLoopRun() on the
 * main thread do not need to call dispatch_main().

This makes me think that there is something missing in GNUstep compared to Cocoa's NSRunLoop to enable this.

Anyone have any idea about this?

--

Johannes Lundberg

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