PDFOutline object is an element in a tree-structured hierarchy that can represent the structure of a PDF document.
- iOS 11.0+
- macOS 10.4+
An outline is an optional component of a PDF document, useful for viewing the structure of the document and for navigating within it.
Outlines are created by the document’s author. If you represent a PDF document outline using outline objects, the root of the hierarchy is obtained from the PDF document itself. This root outline is not visible and serves merely as a container for the visible outlines.