The contextual command bar enables users to have quick access to commands that relate to what they are working on. The command bar changes based on what the user selects. I was in charge of the PowerPoint iOS design. You can see the announcement from Microsoft here (opens in a new tab).
![PowerPoint iOS with Contextual Command bar](style/images/CCB/CCB.png)
![PowerPoint iOS with Contextual Command bar animation](style/images/CCB/ccb.gif)