There are about a thousand different ways to display the time on your iPhone or iPad, but the Chameleon app might be the most interesting. The app uses the device’s rear camera to take a live video feed of whatever is behind the device at the moment, then uses that feed as a background for the app.
The app’s name comes from the chameleon’s ability to blend into its surroundings. The app allows the iPhone or iPad to similarly look just like the setting it happens to be in.
A second mode allows the app to take a sample of a color behind the device, then display just that color as the background. Tapping the numbers toggles their color between black and white, and a swipe of the finger on the device’s screen changes the numbers’ transparency.