No it doesn’t wait and the way you are doing it in that sample is not good practice. dispatch_async is always asynchronous. It’s just that you are enqueueing all the UI blocks to the same queue so the different blocks will run in sequence but parallel with your data processing code. If you want the … Read more
To dispatch something asynchronously, call async on the appropriate queue. For example, you might change this method to do the calculation on a global background queue, and then report the result back on the main queue. By the way, when you do that, you shift from returning the result immediately to using a completion handler … Read more
Dispatching a block to the main queue is usually done from a background queue to signal that some background processing has finished e.g. – (void)doCalculation { //you can use any string instead “com.mycompany.myqueue” dispatch_queue_t backgroundQueue = dispatch_queue_create(“com.mycompany.myqueue”, 0); dispatch_async(backgroundQueue, ^{ int result = <some really long calculation that takes seconds to complete>; dispatch_async(dispatch_get_main_queue(), ^{ [self … Read more
Since the beginning, Swift has provided some facilities for making ObjC and C more Swifty, adding more with each version. Now, in Swift 3, the new “import as member” feature lets frameworks with certain styles of C API — where you have a data type that works sort of like a class, and a bunch … Read more
The main reason you use the default queue over the main queue is to run tasks in the background. For instance, if I am downloading a file from the internet and I want to update the user on the progress of the download, I will run the download in the priority default queue and update … Read more