There is a feature (or two) I would love in the Photos app but since it is not there, I'd like to simply write an app to do it.
Here is what I want it to do, I don't imagine it would be difficult:
For every photo in the Camera Roll (every photo in the app) check to see if that photo is ALSO in any other "album" (which would simply be a pointer of some kind - the actual photo is in one place and it is "tagged" to each album).
Every photo that is NOT tagged to any other album (either automatically tagged like "Selfies" or "Panoramas") or tagged by me (like "Favorites" or any custom album names I've created) I would like to DELETE this photo from the Camera Roll.
My reasoning is as follows: I've fully backed up my camera roll (I would ensure i do this before running this app) and now I want to remove all photos that I have not specifically requested to keep by putting in an album. If I've not tagged it to an album, I don't need it on my phone anymore.
Another cool feature I would love would be to report which photos (by name and folder location) are tagged to which albums. This way I could backup this information in the same place I've backed up all my photos. Backing up the photos keeps the photos themselves, but any album tagging gets lost.
Of course if anyone reads this and recalls seeing an app that is already written that does something like this, please let me know that as well, I have no need to reinvent the wheel!
Otherwise, I am VERY rusty at creating iOS applications - I have none in the store, but I have created one in the past in Objective-c. Any hints at the components or libraries I would utilize to write such an application would be appreciated. A link to the proper library to get me started would be great. If you know the Photos App API really well, and know that what I want to do is impossible, I'd like to hear that too.
Of course, as I do more research (I'll admit I've not done much yet) I will reply to my own thread for the sake of anyone else who finds this question useful.