Build, Test, and Debug Your Design

We provide several tools for building, testing and debugging your app.


You can test your design by using the Preview tool, or by building and running the app. The Preview tool lets you test your design much more quickly than building the app. However, the Preview tool does not replace dynamic lists with actual screen content. To test this level of change, you need to build the app and run it.

See also our Preview Tool reference.


If you’re working as both a designer and a developer, or if you want to build your You.i Platform app to test your design changes, it’s easy to do with our youi-tv command-line interface. Depending on the type of app you’re building, see Building You.i React Native Apps or Building You.i C++ Apps for build information.

Building and testing Cloud Solution apps requires special setup due to the nature client-server relationship. For details, see Building Roku Apps.


The Dev Panel allows you to debug your interface at runtime.

The App Preview Log

Use the App Preview Log to get more information generated when you export or preview your After Effects file. This is particularly useful if you see an unexpected crash when exporting or previewing.

You can access the App Preview Log under the AE Composition menu - select You.i: View Preview App Log.

App Preview Log

Re-export Your Design

If you make changes to your design, don’t forget to export your design again.