Toutday is based around a single iOS Storyboard, with view controllers for each section of the app, and a page view controller to allow switching the current date by swiping left or right. Mood information is stored in a simple Core Data object graph.
Toutday doesn't currently support any form of data synchronization. It would be nice to add Dropbox and iCloud support at some point.
Reporting is currently limited to a simple bar graph and calendar view. I'm currently exploring ways to create more meaningful mood visualizations using D3.js via an embedded UIWebView.
For easier interoperability with existing data analysis tools, or even spreadsheets, I'm planning on adding a simple data export feature.