//创建队列
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
//封装操作
NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"执行耗时操作"++++++++++++++++);
//回到主线程
NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];
[mainQueue addOperationWithBlock:^{
NSLog(@"这是主线程。。。。。");
}];
}];