When working for iOS 7 , I follow the color pattern that recommend on iOS Human Interface Guidelines. However, pickup color is not easy in Xcode. I am using RGB color . When I want to add color code on Xcode , I need to open image from the Guidelines and chose the color with pixelmator.
It’s not easy to use. So, I decided to write color selector for easy my life. I am using UIColor Macro for Xcode. I just want to chose color, copy rgb and paste in to xcode. That all. Don’t want to open images and other apps.
http://saturngod.github.io/iOS7Colors/ is easy to use . Just click , copy the color code. You can chose hex or RGB. Click on the clolor, you can see color with full screen. And then click on the full screen color again , it will go back to the main screen again.