Dispathch Queue

dispatch_queue_t jsonParsingQueue = dispatch_queue_create("jsonParsingQueue", NULL); // execute a task on that queue asynchronously dispatch_async(jsonParsingQueue, ^{ [self citySearchArrayMethod]; // populates the city table with city list // some code on a main thread (delegates, notifications, UI updates...) dispatch_async(dispatch_get_main_queue(), ^{ [self.tableView reloadData]; // load the table with data }); });