Fixed barView's frame.

[pala]

There's no need to minus headerPadding when calculating barView's height.

[terryworona]

The headerPadding is:

The vertical padding between the header and highest chart point (bar, line, etc).

If a user demands padding between the header and chart, each bar should only go as high as the padding boundary and not beyond it.

[pala]

The availableHeight doesn't include headerPadding.

- (CGFloat)availableHeight
{
    return self.bounds.size.height - self.headerView.frame.size.height - self.footerView.frame.size.height - self.headerPadding;
}

CGFloat height = [self normalizedHeightForRawHeight:[self.chartDataDictionary objectForKey:key]];

So the normalized height has already subtracted the headerPadding.

[terryworona]

The availableHeight does include headerPadding; a bar shouldn't extend past this.

All bar's are normalized against self.height - header.height - footer.height - headerPadding

Perhaps I'm overlooking something?

[pala]

All bar's are normalized against self.height - header.height - footer.height - headerPadding

That's right, headerPadding has already been subtracted. The baseline you normalize against has excluded headerPadding.

You can test the demo with headerPadding = 100.0f.

[terryworona]

Ah yes, I see now. Good catch.

We might as well remove the headerPadding from the bar's original Y offset; not that it matters since it's reset in setState: anyways:

barView.frame = CGRectMake(xOffset, self.bounds.size.height - height - self.footerView.frame.size.height, [self barWidth], height + extensionHeight);