Google offers Ice Cream Sandwich guidance to Android app devs

The next major version of Google's Android platform, codenamed Ice Cream Sandwich (ICS), is expected to reach the market in October or November. ICS is expected to bring some significant changes to Android because it will unify Google's tablet and phone variants into a single environment.

Although the SDK is not available yet, Google has published some technical guidance to help third-party application developers start preparing for the ICS transition. An entry posted this week on the Android developer blog describes some steps that developers can take to better accommodate the breadth of screen sizes supported by ICS.

The documentation also provides some insight into how several elements of the Honeycomb user interface could be translated to phone-sized screens in ICS. For example, it includes mockups that show the distinctive Honeycomb action bar on a tablet and a phone. It's not clear, however, if the mockups accurately depict the user experience that will be delivered in ICS.

This seems to suggest that tablet user interfaces developed with standard Honeycomb APIs will largely work on phones in ICS without requiring much modification by third-party developers. That's good news, especially if it ends up being equally true the other way, which would allow phone applications built for ICS to look and feel more native on tablet devices. Google's existing Fragments framework will also help simplify interface scalability by making it easy to transition data-driven applications between single-pane to multi-pane layouts.

Developers who use Fragments and stick to the standard Honeycomb user interface components are on the right track for the upcoming ICS release, but developers who have built more complicated tablet-specific user interfaces or haven't stayed within the boundaries imposed by the documented APIs might face some challenges.

Honeycomb applications that were designed only for the tablet screen size might not scale down correctly on phones. That's a problem, because Android's versioning model doesn't prevent old applications from running on devices with new versions of the operating system—it's going to be possible for users to install Honeycomb tablet applications on ICS phones, even in cases where the result is going to be a very broken application.

In cases where third-party developers can't adapt their tablet software to work well at phone sizes, Google suggests changing the application manifest file to block the application from being installed on devices with small screens.

Another challenge is the large body of legacy devices that aren't going to be updated to ICS. Developers who want to reach the largest possible audience will have to refrain from using the new APIs, which means that it will be harder for them to take advantage of the platform's increasingly sophisticated capabilities for scaling across different screen sizes.

Google has already partially addressed this issue by backporting the Fragments framework and making it available as a static library for older versions of the operating system. It might be beneficial for them to go a step further and do the same with the Action Bar and other critical user interface components that will be designed to scale seamlessly in ICS.

It's going to take some time for the Android application ecosystem to sort all of this out after ICS is released, but Google's approach seems reasonably practical. In theory, developers who are solely targeting ICS APIs might not have to make a significant development investment to get their application working well across tablet and phone form factors.