I am wondering if a comments section in my app must-have report functionality for individual comments.
It's unclear what you are asking. But if your app displays user comments to other users you need to file Guideline 1.2.
1.2 User Generated Content
Apps with user-generated content present particular challenges, ranging from intellectual property infringement to anonymous bullying. To prevent abuse, apps with user-generated content or social networking services must include:
- A method for filtering objectionable material from being posted to the app (note added - I'm not sure they actually mean 'filter' before it is posted)
- A mechanism to report offensive content and timely responses to concerns
- The ability to block abusive users from the service
- Published contact information so users can easily reach you
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