Most of the major iOS Twitter clients already support incoming URLs for status updates. For example, if you want to send a status update to Twitteriffic, just call:

twitterrific://post?message=Message%20Text

For Twitter:

twitter://post?message=Message%20Text

This is strictly a one-way call, however. Why not use x-callback-url to allow passing a return callback for after the user edits and sends the tweet. For example:

[targetAppScheme]://x-callback-url/post?message=Message&
  x-source=[SourceAppName]&
  x-success=[sourceAppScheme]://x-callback-url/tweetPosted

NOTE: arguments should be URL encoded, but were not for legibility.

This could work very much like the existing support in the Twitter app, opening the compose window with the text pre-entered — but after the user taps “Send” and the tweet is successfully posted, fire the callback URL and return the user to where they started.

With this sort of support available, it would be easy for apps to add “Share” functionality that lets their user take advantage of the accounts their users already have setup in their Twitter client, along with all the great composing tools, without forcing the user having leave their app with no clear way back.

If you think this is a cool idea, contact the developer of your favorite Twitter client and let them know. And tell them we’d be happy to help with testing!