How to determine margin of a grouped UITableView (or better, how to set it)?

Question

The grouped UITableView places a margin between the edge of the view and the table cells. Annoyingly (for me) this margin is some function of the width of the view.

Answer 1

I was using Matthew Thomas implementation but it's unreliable (it's broken if you use autorotation in your controllers) and has a lot of hardcoded code... I realized that there is a very simple solution, my implementation is a single line of code:

- (float)cellMargins
{
    return self.backgroundView.frame.origin.x * 2;
}

This is far better IMO :)

EDIT: my implementation was unreliable too (it does not work properly when switching to/from editing mode), this is my final implementation (I handled right and left margins separately):

- (float)leftMargin
{
    return self.contentView.frame.origin.x;
}

- (float)rightMargin
{
    CGRect frame = self.contentView.frame;
    float containerWidth = frame.size.width;
    float margin = self.frame.size.width - (containerWidth + frame.origin.x);
    return margin;
}

- (float)cellMargins
{
    return ([self leftMargin] + [self rightMargin]);
}