So I want to make either a website or iPhone app and it will have 3 different types of users that all have different functions. I'll refer to these as user 1, user 2, and user 3. The lowest user, user 1, should be able to either take or upload a picture and send it with comments to user 2. My question is what would be the best way to implement this? How difficult would it be to do this with PHP for a web based application vs using Apple's Swift language for an iPhone app?
As for the database part, I know the app would require a database, but how would that integrate with the sending of info back and forth between the different user types?
Also, if I'm working with PHP, what would be the best way to go about creating the 3 different users with a login system? Are there any existing frameworks or tools out there that would do this for me, because I read that by doing it yourself you are bound to leave security holes open which would make it insecure.