Handy category for sampling pixel data from UIImage…

https://github.com/Club15CC/Marshmallows/tree/master/Source/UIKit

A UIImage category for

• Getting pixel byte data into an NSData object
• Sampling pixel colour data at a point
• Sampling an even selection of pixels from a range (for using gradients swatches as colour profiles).

Many thanks to the help in this SO questions.