Pantone just released their Color Match Card which allows you to measure any color with your iPhone.
https://www.pantone.com/products/color-capture-devices/pantone-color-match-card?utm_source=googlefeed&gclid=Cj0KCQjwpNr4BRDYARIsAADIx9yFBJKjVAwHIoPgSu8KAk_VjamRBCb8txP1SER67Bvx1MuCVfwzES0aAvtOEALw_wcB