Tableview滚动到顶部不会一路走来

Question

我有一个导航栏，我手动编码以根据scrollView（tableView）的偏移设置框架动画。下面是未展开的截图。

现在调用setScrollOffset:(0,0)后scrollsToTop，而不是我手动 - 例如通过点按状态栏），scrollview滚动到顶部，但是在使用的位置没有导航栏。我可以在动画发生后手动滚动最后44px左右，但显然这不是预期的行为。

以下是我隐藏导航栏的代码：

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGRect frame = self.navigationController.navigationBar.frame;
    CGFloat size = frame.size.height - kMacro1;
    CGFloat framePercentageHidden = ((kMacro2 - frame.origin.y) / (frame.size.height - 1));
    CGFloat scrollOffset = scrollView.contentOffset.y;
    CGFloat scrollDiff = scrollOffset - self.previousScrollViewYOffset;
    CGFloat scrollHeight = scrollView.frame.size.height;
    CGFloat scrollContentSizeHeight = scrollView.contentSize.height + scrollView.contentInset.bottom;

    if (scrollOffset <= -scrollView.contentInset.top) {
        frame.origin.y = kMacro2;
    } else if ((scrollOffset + scrollHeight) >= scrollContentSizeHeight) {
        frame.origin.y = -size;
    } else {
        frame.origin.y = MIN(kMacro2, MAX(-size, frame.origin.y - scrollDiff));
    }

    [self.navigationController.navigationBar setFrame:frame];
    [self updateBarButtonItems:(1 - framePercentageHidden)];
    self.previousScrollViewYOffset = scrollOffset;
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    [self stoppedScrolling];
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView
                  willDecelerate:(BOOL)decelerate
{
    if (!decelerate) {
        [self stoppedScrolling];
    }
}

- (void)stoppedScrolling
{
    CGRect frame = self.navigationController.navigationBar.frame;
    if (frame.origin.y < kMacro2) {
        [self animateNavBarTo:-(frame.size.height - kMacro1)];
    }
}

- (void)animateNavBarTo:(CGFloat)y
{
    [UIView animateWithDuration:0.2 animations:^{
        CGRect frame = self.navigationController.navigationBar.frame;
        CGFloat alpha = (frame.origin.y >= y ? 0 : 1);
        frame.origin.y = y;
        [self.navigationController.navigationBar setFrame:frame];
        [self updateBarButtonItems:alpha];
    }];
}