grand-central-dispatch

I found some information in the net to create a singleton class using GCD. Thats cool because it's thread-safe with very low overhead. Sadly I could not find complete solutions but only snippets of the sharedInstance method. So I made my own class using the trial and error method - and et voila - the following came out: @implementation MySingleton // MARK: - // MARK: Singleton Pattern using GCD + (id)allocWithZone:(NSZone *)zone { return [[self sharedInstance] retain]; } - (id)copyWithZone:(NSZone *)zone { return self; } - (id)autorelease { return self; } - (oneway void)release { /* Singletons

I have a callback which might come from any thread. When I get this callback, then I would like to perform a certain task on the main thread. Do I need to check whether I already am on the main thread - or is there any penalty by not performing this check befora calling the code below? dispatch_async(dispatch_get_main_queue(), ^{ // do work here }); No, you do not need to check whether you’re already on the main thread. By dispatching the block to the main queue, you’re just scheduling the block to be executed serially on the main thread, which happens when the corresponding run loop is run.

I'm struggling to fully understand the concurrent and serial queues in GCD. I have some issues and hoping someone can answer me clearly and at the point. I'm reading that serial queues are created and used in order to execute tasks one after the other. However, what happens if: I create a serial queue I use dispatch_async (on the serial queue I just created) three times to dispatch three blocks A,B,C Will the three blocks be executed: in order A,B,C because the queue is serial OR concurrently (in the same time on parralel threads) because I used ASYNC dispatch I'm reading that I can use

I am writing a command line application in Swift using a third-party framework that (if I understand the code correctly) relies on GCD callbacks to complete certain actions when a socket receives data. In order to better understand the framework, I have been playing around with a sample Cocoa application the framework's author wrote to go along with the framework. Because the sample application is a Cocoa application, the run loops are handled automatically. I'm including snippets of code from the sample application (MIT license) to give an idea of how it works: class AppDelegate: NSObject,

I have been using with success, grand central dispatch in my apps, but I was wondering what is the real advantage of using something like this: dispatch_async(dispatch_get_main_queue(), ^{ ... do stuff or even dispatch_sync(dispatch_get_main_queue(), ^{ ... do stuff I mean, in both cases you are firing a block to be executed on the main thread, exactly where the app runs and this will not help to reduce the load. In the first case you don't have any control when the block will run. I have seen cases of blocks being executed half a second after you fire them. The second case, it is similar to