While working on the MailComposer and MessageComposer functions, I also quickly added the SocialComposer functions for posting to Facebook, Twitter, SinaWeibo and TencentWeibo.
Screenshots are in German, but whatever localization you use, the dialog will look correct in your language.
For both you can check if service is configured for the user and show the panel with your message to send. You can define message text, add URLs and images from both container fields and image files on the device. The user can change text and press send. You get a script triggered when the user is finished.
We also have SocialRequest functions to post without showing a dialog and those do work on iOS now.
Will be soon available in next plugin version. Or email if you like to try today.