[AJ007]

Read these "Bugs, Caveats, Side Notes" published on the Onion Browser app's web site:

Major iOS SDK Limitation: Websites using HTML5 <video> tags will leak <video>-related DNS queries and data transfer outside of Tor. This includes YouTube, Vimeo, and any website using iOS-compatible HTML5 video. This is a behavior of the embedded QuickTime player and there is currently no known workaround. (h/t to josyw.)

iOS SDK Limitation: Javascript cannot be disabled in the `UIWebView`, so script-based detection may identify your device even if User-Agent Spoofing is enabled. iOS SDK Limitation: Related to above, the HTML5 Geolocation API cannot be disabled. The browser will ask you for permission to access your location if a website asks for it via the HTML5 Geolocation API. If you allow this, then said website will (obviously) know your actual current location.

That doesn't sound remotely safe to me.