iOS 滑动页面的时候让tabbar下移到消失，nav隐藏

iOS 滑动页面的时候让tabbar下移到消失，nav隐藏，停止滑动的时候tabbar和nav出现

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
[UIView animateWithDuration:1 animations:^{
self.tabBarController.tabBar.transform = CGAffineTransformMakeTranslation(0, 49);
[UIView animateWithDuration:5 animations:^{
self.navigationController.navigationBar.alpha = 0;
}];
}];

}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
[UIView animateWithDuration:1 animations:^{
self.tabBarController.tabBar.transform = CGAffineTransformIdentity;
self.navigationController.navigationBar.alpha = 1;
}];
}