- (void)viewDidLoad {

    [super viewDidLoad];

    if ([self respondsToSelector:@selector(automaticallyAdjustsScrollViewInsets)]) {

        self.automaticallyAdjustsScrollViewInsets = NO;

    }

    //  1.tableView

    [self.view addSubview:self.tableView];

}

#pragma mark - 滑动隐藏导航栏

- (void)scrollViewDidScroll:(UIScrollView *)scrollView

{

    CGFloat offsetY = scrollView.contentOffset.y + _tableView.contentInset.top;//注意

    CGFloat panTranslationY = [scrollView.panGestureRecognizer translationInView:self.tableView].y;

    if (offsetY > ) {

        if (panTranslationY > ) { //下滑趋势，显示

            [self.navigationController setNavigationBarHidden:NO animated:YES];

        }

        else {  //上滑趋势，隐藏

            [self.navigationController setNavigationBarHidden:YES animated:YES];

        }

    }

    else {

        [self.navigationController setNavigationBarHidden:NO animated:YES];

    }

//    NSLog(@"%lf %lf", [scrollView.panGestureRecognizer translationInView:self.tableView].y, offsetY);

}

[[[self.navigationController.navigationBar subviews] objectAtIndex:] setAlpha:_alphaMemory];