The Table of Contents table that appears when the user presses the TOC toolbar icon from inside an article needs to have a Close button, otherwise some users won't be able to close the table if they open it by mistake or decide that they do not want to choose any item. Users of the assistive technologies VoiceOver and Switch Control cannot "tap outside".
Although there is a special way to perform an "Escape" action in both VoiceOver and Switch Control (see also T124593), this should not be relied on because it is intended rather as a shortcut and not all users will know it or be able to perform it (escape in voiceover requires a rather complicated two-finger gesture).
There is also a general usability concern – even perfectly healthy users should have a clear and easy way how to dismiss the table.
The Close button should ideally be placed near the top of the screen to be easily reachable even if the table contains many items, perhaps in the top-right corner, to the right of the "CONTENTS" label.
Proposed solution
https://dl.dropboxusercontent.com/spa/tuyaic6q75gkcv4/Exports/Untitled%202/Untitled%202.html
Tap on the TOC button.