第三十九篇、NavBar动态隐藏、设置透明、毛玻璃效果

1.动态隐藏

- (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 > 64) {
        if (panTranslationY > 0) { //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);
}

2.设置透明

[[[self.navigationController.navigationBar subviews] objectAtIndex:0] setAlpha:_alphaMemory];