GCD

dispatch_queue_t queue=dispatch_queue_create("luoliping", DISPATCH_QUEUE_SERIAL);

dispatch_async(queue, ^{
NSLog(@"%@",[NSThread currentThread]);

});

dispatch_suspend(queue);
dispatch_resume(queue);

dispatch_async(queue, ^{
NSLog(@"%@",[NSThread currentThread]);

});

dispatch_async(queue, ^{
NSLog(@"%@",[NSThread currentThread]);

});

dispatch_async(dispatch_get_global_queue(0, 0), ^{
NSLog(@"2-%d",[NSThread isMainThread]);

dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"2-%d",[NSThread isMainThread]);
//刷新表
[_tableView reloadData];
});
});