I don't know what iOS 8 brings... but for iOS 7 (and iOS 8, if it doesn't provide a mechanism) I wrote Choosy
. It lets you make a Twitter link and allows your users to pick from installed Twitter clients. Same for maps, browser, etc. This includes support for x-callback with apps that implement it.
It's in beta, the code will be refactored to be better, I'm sure, and all help would be appreciated! But it's pretty magical with the apps it currently knows about.
Check it out, comment, submit issues, and holler if you're implementing it and are stuck on anything.