gistfile1.txt

NSArray *myMainThreadShit = nil;

dispatch_async( dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0 ), ^{
    // do massive intensive shit
    
    NSArray *myShit = [MyModel getMyShit];

    dispatch_async( dispatch_get_main_queue(), ^{
        // this is on main thread
        myMainThreadShit = [myShit copy];
    });
});

return myMainThreadShit;