How To Invert Color in iOS 9
In iOS 9, you can easily invert colors of your iPhones and iPads. Here are two ways to do it:
Technique #1: Change Color From Settings
To activate the color change, go to Settings -> General -> Accessibility. Now enable “Invert colors” to get the black & white effect on your iPhone / iPad.
Technique #2: Ask Siri To Invert Colors
Open Siri from your iPhone / iPad, and ask Siri: “Turn on invert colors.”
Siri will respond you with: “OK, I turned on Invert colors.” It’s that simple!