RT

How to convert UIColor to hex in Swift

Here’s a simple extension to convert a UIColor to a hex string in Swift:

extension UIColor {
    func toHex() -> String {
        var red: CGFloat = 0
        var green: CGFloat = 0
        var blue: CGFloat = 0
        var alpha: CGFloat = 0

        guard self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) else {
            assertionFailure("Failed to get RGBA components from UIColor")
            return "#000000"
        }

        // Clamp components to [0.0, 1.0]
        red = max(0, min(1, red))
        green = max(0, min(1, green))
        blue = max(0, min(1, blue))
        alpha = max(0, min(1, alpha))

        if alpha == 1 {
            // RGB
            return String(
                format: "#%02lX%02lX%02lX",
                Int(round(red * 255)),
                Int(round(green * 255)),
                Int(round(blue * 255))
            )
        } else {
            // RGBA
            return String(
                format: "#%02lX%02lX%02lX%02lX",
                Int(round(red * 255)),
                Int(round(green * 255)),
                Int(round(blue * 255)),
                Int(round(alpha * 255))
            )
        }
    }
}

Display P3 colors are truncated to fall within the sRGB gamut.

Usage

let color = UIColor(red: 0.5, green: 0.5, blue: 0.5, alpha: 1)
print(color.toHex()) // #808080

See also