How to add a UIToolbar
The library will always fill the view of the
MFDocumentViewController subclass, that is
DocumentViewController in the sample.
To have a toolbar at the bottom, you can either add you own
toolbar as overlay (it will cover the bottom of the pdf's view),
and show/hide it as necessary, or as an alternative, present your
DocumentViewController with a
UINavigationController and use the
UINavigationController default toolbar (it is hidden
The latter will require you to manually set the toolbar items in
viewDidAppear:animated:, since doing earlier will
cause the toolbar to discard them too soon.