A mostly complete iPad app description

Along the lines in my previous blog post: Preparing a full description my first iPad App, here is a mostly complete description of my first iPad app that I'm planning to build and sell on the App Store.

Application goals
The goal of this application is to browse pictures on the micro blogging platform Tumblr.

Design principals

• Pictures are at the centre of the user experience and occupy all the space available.
• Look at other iPad photo browsers for inspiration.
• Prefer a dark theme to make it look like a dark room experience and make pictures stand out.
• Design the application toolbars or spaces for later feature expandability (like allowing the liking of posts, re-bloging to followers, etc.).
• Provide a quick browser mode and a closer view design mode and think about the way the user will switch between modes.

Interaction metaphor

• One display mode: a grid view but each picture will allow a close up view for each picture.
• By default, in the grid view, pictures are shown with a 4 x 3 grid with rounded corners and nothing else. Tapping with two fingers to toggle buttons or overlaid picture's metadata.
•  A variant of this grid view could be added later: grouped view: all pictures organized by image's source instead of the timeline).

Application features

• Support the two basic iPad orientations (portrait and landscape).
• User will be able to browse pictures only (the application will skip blog posts with other media types);
• User will be able to browse Tumblr without being authenticated (if the API allows it, otherwise the user will be presented with a view background asking him to sign in).
• iOS 5 only required to support integrated Twitter client. 
• Share picture link on social networks, send links by mail or save picture into the photo app.
• Authentication process details starts from top toolbar (when application is first started, the app background will provide a visual cue to the user asking him to authenticate to the Tumblr service).
• Authenticate the user to the his Tumblr Dashboard.
• Users with multiple accounts is supported (sign off then sign in).
• No settings available in Settings.app, only inside the application:
• In-App settings: Configure Twitter sharing;
• In-App settings: Configure Facebook sharing;
• In-App settings: Configure Save image: as seen or full res
• In-App settings: Configure a PIN
• In-App settings: Allow grouping of picture by sources or timeline only (in a future version)

In the next blog post, I'm going to expose the visual details of this application textually and I may include one on my first application sketch. Stay tuned.