UIScrollView滚动时隐藏底部导航栏问题

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
NSLog(@"开始滚动");
int currentPostion = scrollView.contentOffset.y;

if (currentPostion -
_lastPosition > 20 && currentPostion >0) {

_lastPosition = currentPostion;

NSLog(@"ScrollUp now");

self.tabBarController.tabBar.hidden
=YES;

[self.navigationControllersetNavigationBarHidden:YESanimated:YES];

}

else
if ((_lastPosition - currentPostion >20) && (currentPostion <= scrollView.contentSize.height-scrollView.bounds.size.height-20)
)
{

_lastPosition = currentPostion;

NSLog(@"ScrollDown now");

self.tabBarController.tabBar.hidden
=NO;//隐藏时，没有动画效果

[self.navigationControllersetNavigationBarHidden:NOanimated:YES];

}
}

转载自：http://blog.csdn.net/caryaliu/article/details/7907196

自：在我的工程中，我是把 _lastPosition = 0； 然后把那个 25 改成了 160

有时候我们需要检测当前UIScrollView的滑动方向来做出相应的处理，可以借助UIScrollView的delegate函数来实现， 下面的例子可以检测到UIScrollview当前是向上滑动还是向下滑动：

[cpp] view
plaincopy

int _lastPosition; //A variable define in headfile

- (void)scrollViewDidScroll:(UIScrollView *)scrollView{

int currentPostion = scrollView.contentOffset.y;

if (currentPostion - _lastPosition > 25) {

_lastPosition = currentPostion;

NSLog(@"ScrollUp now");

}

else if (_lastPosition - currentPostion > 25)

{

_lastPosition = currentPostion;

NSLog(@"ScrollDown now");

}

}

25 可以是任意数字，可根据自己的需要来设定。