culumn

Add build test for `Carthage` to travis ci step.

These methods have boolean return value indicating compatible for color space. https://developer.apple.com/documentation/uikit/uicolor/1621949-gethue https://developer.apple.com/documentation/uikit/uicolor/1621919-getred

Should redraw the view.

Should add code comments for description.

About current implementation, if the brightness is changed, redraw the wheel image. So the brightness is changed consecutively, it takes the heavy loading.

Current example app is not completed to implement.

Should add the tests for this library.