Last week, I started discussing the CategoryBar changes when moving from Series 40 full touch to the new Nokia Asha UI.
Another big difference is how back-stepping now works; whereas in full touch apps you have to place the “Back” button on the screen, with the Nokia Asha UI you mustn’t do that anymore. Nokia Asha has a hardware “Back” key that takes care of the back-stepping; you just need to define an “EXIT”-typed command to your main view (this will let the user exit the MIDlet) and “BACK”-typed Commands for all other views to let the user step backwards in navigation hierarchy.
In the above image you see how “Back” has moved from being a textual label (1: touch and type), to being a back icon (2: full touch), and now to being a hardware key (3: Nokia Asha).
The basic rules of back-stepping don’t change, so “Back” is still hierarchical rather than historical. What this mean in practice is that after drilling down in the app hierarchy, the way back to the app’s main level is via the hardware back key. If the user is navigating between parallel views with the CategoryBar (i.e., not drilling down but staying on the main level), then hierarchically thinking the user remains on the main level, and thus the “Back” key functions as “Exit”.
Since there is a dedicated hardware key for backstepping, no software “Back” or “Exit” is allowed on-screen. Games are the only exception to this rule; they are allowed to have “Back” and “Exit” on screen. Two things to remember, though:
- Having software back and exit is not recommended even for games, as they duplicate the back-stepping functionality.
- The hardware back key must still always work as a way to step back, even if there is a Pause/Back software key in use.
Following these guidelines helps retain consistency between how the phone works and how any app, be it a game or a social app, works. Read the whole story about back-stepping from the Navigation models chapter (scroll down the page a bit…) in the Nokia Asha design guidelines.