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I'm new to GCD principles and GCDAsyncSocket, but I'm using it in my project. I initialize the GCD socket in the AppDelegate with:

self.socket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];

Now, everything runs fine, sending and receiving works fine. But, if the socket receives a lot of data very fast (like a 1000 or so messages from a 'for loop' from the server), the app's UI freezes till it has received everything (Although there are no errors in the received messages).

So what do I need to change to not let the UI freeze? Is it because it is using "dispatch_get_main_queue()", do I need to use another queue? if so, how should I go about it? Or do I use threading or something like that?

Atomix
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raj
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1 Answers1

2

Try creating your own concurrent serial background queue (turns out your not allowed to use a concurrent one), for example

dispatch_queue_t queue = dispatch_queue_create("com.yourid.queue", DISPATCH_QUEUE_SERIAL);
self.socket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue: queue];

Alternatively you can pass 'NULL' and GCDAsyncSocket will create its own queue.

This should call the delegate methods in a background queue and hopefully stop your UI from freezing. The important thing to note here is, you can't update UI Elements on a background queue, so you have to do something like this in your delegate methods:

- (void)socket:(GCDAsyncSocket *)sender didConnectToHost:(NSString *)host port:(UInt16)port
{
    //Do some calculations (in background queue)

    dispatch_async(dispatch_get_main_queue(), ^{
        //Update UI elements (in main queue)
    });
}

(I hope I remembered this correctly)

Atomix
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  • I read the GCD docs and figured this out myself. The only difference being that the custom dispatch queue which you've created is a concurrent one, and I believe that a GCDAsyncSocket delegate queue requires to be serial (so that all incoming/outgoing messages are processed one after the other serially). And so a serial one works well in my implementation, but I haven't tested a concurrent one. If you can assure me that a concurrent one works as well, I'll mark this answer right. – raj Apr 29 '15 at 04:50
  • I did some more research and edited my answer. Turns out you're not allowed to use a concurrent queue... – Atomix Apr 29 '15 at 07:01