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

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

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.

Need to know Objective-C fast?

I wrote a book dedicated to teaching Objective-C to developers who already know Swift – it's the fastest way to get up to speed!

MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Click here to visit the Hacking with Swift store >>