title: Calling dispatch_async(dispatch_get_main_queue() ) inside a NSOperationqueue
body: <p>I'm performing a few <code>NSInvocationOperation</code>s by adding them to a <code>NSOperationQueue</code>. While making changes to UI, I call the <code>dispatch_async(dispatch_get_main_queue() )</code> instead of <code>[NSOperationQueue mainQueue] addOperationWithBlock:^(void){}]</code>. Does this sound logically right? I'm still trying to execute the block on the main thread.</p>