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Efficiency: Creation of new notes is not very efficient in this design, since on first launch the user must create a class to categorize the notes in first. Even after that, users can't just create notes and decide where to save them later, like they might if they were saving a file on their computer. Instead, they have to decide where the notes are categorized first. However, the efficiency sacrificed in the creation of notes is gained when reviewing the notes, since imposing an organizational system saves users the trouble of inventing one later. Furthermore, the paned display that allows you to view the entire hierarchy at once makes it easier to see where you might have put notes that you want to review. The search bar also allows for efficient locating of notes.
Safety: Note and category creation could result in creating things that you don't need, or having the wrong names. However, this is undoable by renaming or deleting those items. A confirmation dialog is used before a delete to prevent accidental deletion. Photos in the camera roll can be deleted by selecting them and using delete/backspace, or by dragging them to the trashcan that appears at the bottom of the roll on dragging. Any mistakes that are made during text editing should be easily reversible by using the normal text editor functionality or using the undo/redo stream.
Design 2
In this design, notes are stored in a hierarchy that mimics a traditional directory hierarchy.
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