Original code by Brian Advent : https://www.youtube.com/watch?v=Wz6-IQV_qDw
Following along with mr. advent's code from his video tutorial from 4th december, 2016, I decided to make his code a little more swift like, and a lot safer.
I also needed to make it work with a SpriteKitLabel node.
This code also allows for units to be used after the number e.g. "22kg" / "48.5ib" (nb. this code will not convert between units however)
This code may be used in a commercial application if desired.