您可以尝试以下步骤:
1. 声明导航栏,使用一个常量表示导航栏的高度,并声明两个 BOOL 变量:
UINavigationBar *navBar
static const CGFloat kNavBarHeight = 60.0f
BOOL webViewScrollIsDragging
BOOL webViewScrollIsDecelerating
2. 在viewDidLoad中写入以下内容:
[webView.scrollView setContentInset:UIEdgeInsetsMake(kNavBarHeight, 0, 0, 0)];
[webView.scrollView setScrollIndicatorInsets:UIEdgeInsetsMake(kNavBarHeight, 0, 0, 0)];
[webView.scrollView setContentOffset:CGPointMake(0, -kNavBarHeight) animated:NO];
webView.scrollView.delegate = self;
然后,初始化并将您的UINavigationBar
作为self.view
的子视图添加到原点(还要确保您的UIWebView
具有相同的原点,即(0,0))。
3. 实现UIScrollViewDelegate
方法(不要忘记添加UIScrollViewDelegate
协议):
#pragma mark - UIScrollViewDelegate Methods
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView == webview.scrollView)
{
if (scrollView.contentOffset.y == 1 && !webViewScrollIsDragging && !webViewScrollIsDecelerating)
{
[UIView animateWithDuration:0.3
delay:0.0
options: UIViewAnimationCurveEaseOut
animations:^(void) {
CGRect navBarFrame = CGRectMake(0,-scrollView.contentOffset.y-kNavBarHeight, self.view.bounds.size.width, kNavBarHeight);
navBar.frame = navBarFrame;
}
completion:nil];
}
else
{
CGRect navBarFrame = CGRectMake(0,-scrollView.contentOffset.y-kNavBarHeight, self.view.bounds.size.width, kNavBarHeight);
navBar.frame = navBarFrame;
}
if (scrollView.contentOffset.y < -kNavBarHeight)
{
[webview.scrollView setScrollIndicatorInsets:UIEdgeInsetsMake(fabsf(scrollView.contentOffset.y), 0, 0, 0)];
}
}
}
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
if (scrollView == webview.scrollView)
{
webViewScrollIsDragging = YES;
}
}
- (void) scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
if (scrollView == webview.scrollView)
{
webViewScrollIsDragging = NO;
}
}
- (void) scrollViewWillBeginDecelerating:(UIScrollView *)scrollView
{
if (scrollView == webview.scrollView)
{
webViewScrollIsDecelerating = YES;
}
}
- (void) scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
if (scrollView == webview.scrollView)
{
webViewScrollIsDecelerating = NO;
}
}