UIAlertView提示框自动消失

UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@""                                                message:@"感谢您提交宝贵意见"                                               delegate:self                                     cancelButtonTitle:@"确认"                                     otherButtonTitles:nil, nil];[alert show];//处理耗时线程dispatch_async(dispatch_get_global_queue(0, 0), ^{    [NSThread sleepForTimeInterval:10];//休眠10秒    //通知主线程更新ui    dispatch_async(dispatch_get_main_queue(), ^{        [alert dismissWithClickedButtonIndex:0 animated:YES];    });});