ios - table header view height is wrong when using auto layout, IB, and font sizes

Question

I am trying to create a header view for my uiTableView (not a section header, I already have those.) I have set up an XIB in interface builder. All the connections are hooked up and it runs beautifully... except the table doesn't give it enough room! My problem is that the top of the table overlaps the table's header by a little.

My XIB is setup with autlayout for all the buttons, and IB is happy that the constraints don't conflict / ambiguous. The view is set to Freeform size, which in my case ended up being 320 x 471. Then in constraints for the view, I set an intrinsic size for the view of the same.

Now this works perfectly with my table. Everything looks great. But if I manually change any of the fonts in the header view with code, the layout makes the view bigger, and it ends up underneath my table.

Any ideas how to get the tableviewcontroller to leave enough room for the header view after setting fonts and sizes? I hope I've made sense explaining this.

Answer 1

Note: A Swift 3+ version can be found here: https://gist.github.com/marcoarment/1105553afba6b4900c10#gistcomment-1933639

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The idea is to calculate header's height with help of systemLayoutSizeFittingSize:targetSize.

Returns the size of the view that satisfies the constraints it holds. Determines the best size of the view considering all constraints it holds and those of its subviews.

After changing header's height it is necessary to reassign tableHeaderView property to adjust table cells.

Based on this answer: Using Auto Layout in UITableView for dynamic cell layouts & variable row heights

- (void)sizeHeaderToFit
{
    UIView *header = self.tableView.tableHeaderView;

    [header setNeedsLayout];
    [header layoutIfNeeded];

    CGFloat height = [header systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].height;
    CGRect frame = header.frame;

    frame.size.height = height;
    header.frame = frame;

    self.tableView.tableHeaderView = header;
}