While I don't think you can create your own bookmarks, you can see the contents if your PDFs are properly formatted already to include them, which they should be for textbooks and anything official (not always for self-published material or grey literature). You just need to enable the sidebar at the top left of the toolbar, and switch to the last of the three options for viewing.
If your PDF doesn't show any bookmarks, there are workarounds: 1. You can create bookmarks in another PDF software you have that allows it (eg Acrobat Pro allows you to create bookmarks from a structure, which is great if your publisher hasn't done that but has used proper headings), and then import. 2. As a workaround, you can also just highlight the text as an annotation (eg the Endnotes or Chapter headings) - you can click on annotations in the sidebars and it will jump the PDF back and forth.
Ah sorry - I was referring to the desktop version! I don't tend to read long documents on ios, so hadn't noticed it wasn't there. Makes sense if they could add it. For my simple needs, the navigation thumbnails down the bottom tend to be enough.
The annotations hack would work in a pinch, or if it was a textbook, you could just highlight the PDF in another reader and import the annotations.
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If your PDF doesn't show any bookmarks, there are workarounds:
1. You can create bookmarks in another PDF software you have that allows it (eg Acrobat Pro allows you to create bookmarks from a structure, which is great if your publisher hasn't done that but has used proper headings), and then import.
2. As a workaround, you can also just highlight the text as an annotation (eg the Endnotes or Chapter headings) - you can click on annotations in the sidebars and it will jump the PDF back and forth.
The annotations hack would work in a pinch, or if it was a textbook, you could just highlight the PDF in another reader and import the annotations.