Navigating Direct Messages w/ the Keyboard and Voice Over (iOS)
In Twitterrific, direct messages are always displayed as conversation threads, to read & interact with them double-tap on any message in the DM list to open the DM thread with that particular person. In addition, a custom action is available on each item in the main Messages screen to view the user's profile. To access that, when on any item, select Actions from the VoiceOver rotor if it isn't selected automatically, then swipe up or down to the "View Profile" item, and then double-tap. Another action allows you to mark a thread as unread.
Inside each direct message thread, messages are shown in the order they came in, with the newest messages at the bottom, as is also the case in the iOS Messages app. This thread view takes up most of the screen, and you can swipe left and right to go from message to message. Note that you should first tap on a message to put VoiceOver focus there.
The rest of the screen is made up of a header containing the other participant's name, and a Close button. At the bottom, there is a text field and a Send button, where you compose your reply to a direct message, and use the Send button to send it. The text field is multi-line, so you can use the iOS keyboard's Enter key to insert a new paragraph as needed.