I have read the Apple documentation. They list the apps registered, yet in their example they use a handler not mentioned. https://developer.apple.com/iphone/library/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/ApplicationEnvironment/chapter_3_section_6.html
This post attempts to list the handlers. But it too appears incomplete since the iPod handler is not listed. http://quinagh.com/applookup/index.php/2009/01/07/iphone-apps-with-special-url-shortcuts/
Is there a complete list available? Does anyone know if the Photos app has a registered handler or not for certain?
There is, afaik, no way to tell beyond those that are documented.