NEW: Master Swift design patterns with my latest book! >>

How to read the red, green, blue, and alpha color components from a UIColor

Written by Paul Hudson    @twostraws

Creating a UIColor from red, green, blue, and alpha (RGBA) is easy enough:

let color = UIColor(red: 0.8, green: 0.1, blue: 0.5, alpha: 1)

But when you want to read those values back, you need to do a little more work. UIColor has a built-in method called getRed(), which unpacks the RGBA values into variable floats – you need to create four variables first, then pass them in by reference:

var red: CGFloat = 0
var green: CGFloat = 0
var blue: CGFloat = 0
var alpha: CGFloat = 0

color.getRed(&red, green: &green, blue: &blue, alpha: &alpha)

When that runs, red will have 0.8, green will have 0.1, and so on.

Because this is a pain to use you might find it best to wrap it up in an extension:

extension UIColor {
    var rgba: (red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) {
        var red: CGFloat = 0
        var green: CGFloat = 0
        var blue: CGFloat = 0
        var alpha: CGFloat = 0
        getRed(&red, green: &green, blue: &blue, alpha: &alpha)

        return (red, green, blue, alpha)
    }
}

Now you can use color.rgba to get back a tuple of all four color values.

Available from iOS 5.0

Did this solution work for you? Please pass it on!

Other people are reading…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

Learn Server-Side Swift now!

Take your Swift code to the server and become a full-stack developer with my latest book: Server-Side Swift!

Click here to visit the Hacking with Swift store >>