Xcode 8+, iOS 10+
I recently faced this problem and none of the posted answers did it. It turns out that with the release of iOS 10 SDK, the UIColor initializer init(red:green:blue:alpha:) now uses the extended sRGB range, so you have to set accordingly when configuring your color values on the Storyboard.
See Apple’s documentation: https://developer.apple.com/reference/uikit/uicolor/1621925-init