GCD background and main thread task

GCD-background-main-thread

//Start an activity indicator here
 
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
 
    //Call your function or whatever work that needs to be done
    //Code in this part is run on a background thread
 
    dispatch_async(dispatch_get_main_queue(), ^(void) {
 
        //Stop your activity indicator or anything else with the GUI
        //Code here is run on the main thread
 
    });
});