grand-central-dispatch

I'm using the Kiwi testing framework to test an authentication method in my app. The test freezes at a call to dispatch_sync which looks like this: dispatch_queue_t main = dispatch_get_main_queue(); dispatch_sync(main, ^ { [[NSNotificationCenter defaultCenter] postNotificationName:kNotificationAuthenticationSuccess object:nil userInfo:ret]; }); I'd like to know why it freezes there, if anyone has any hints. For the second part of your question regarding the hint on the freeze: When calling dispatch_sync on a queue, always verify that this queue is not already the current queue ( dispatch_get

Starting to learn about core data and dispatch_async. There is a block of code to get url of image from set of data and set it to model of core data like below dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{ NSString *urlString = [[[photoDictionary valueForKey:@"images"] objectAtIndex:0] valueForKey:@"url"]; NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlString]]; dispatch_async(dispatch_get_main_queue(), ^{ [photoModel setValue:imageData forKey:@"photoImageData"]; Can somebody explain to me why we use dispatch_get_global_queue for the

I want to be able to execute a block on the next run loop iteration. It's not so important whether it gets executed at the beginning or the end of the next run loop, just that execution is deferred until all code in the current run loop has finished executing. I know the following doesn't work because it gets interleaved with the main run loop so my code might execute on the next run loop but it might not. dispatch_async(dispatch_get_main_queue(),^{ //my code }); The following I believe suffers the same problem as above: dispatch_after(DISPATCH_TIME_NOW, dispatch_get_main_queue(), ^(void){ /

Recently, I had the need for a function that I could use to guarantee synchronous execution of a given block on a particular serial dispatch queue. There was the possibility that this shared function could be called from something already running on that queue, so I needed to check for this case in order to prevent a deadlock from a synchronous dispatch to the same queue. I used code like the following to do this: void runSynchronouslyOnVideoProcessingQueue(void (^block)(void)) { dispatch_queue_t videoProcessingQueue = [GPUImageOpenGLESContext sharedOpenGLESQueue]; if (dispatch_get_current