Cooler is a program created for iOS and Mac OS X developers. This application enables you to convert hex values to UIColor and NSColor formats and automatically copies the results to your clipboard. You can then paste the obtained color codes to the utility which you use to write your source code.
There are two ways to provide an input shade code: enter its hex value or select the color from Mac's palette application. Afterwards, you can choose the preferred output format (UIColor (Obj-C), UIColor (Swift) or NSColor (Obj-C)) and click the Generate button. The program automatically copies the resulted color code to your clipboard and displays a notification just under you Menu Bar.
Other than that, not much more can be said about Cooler. It simply does what's being stated on its homepage, without slowing down the performance of your Mac.
The one thing I'd add would be an option to pick color codes from my desktops and paste them within Cooler's interface.
In conclusion, you should install this program on your Mac if you wish to easily convert hex values to UIColor and NSColor formats. The application is very simple to handle, immediately offers you the results you need, and is free of charge.