Comparing 2 UIColor(s)

Question

This must have been asked before, but I cannot find a suitable reference. I have found this question, but that compares three numbers with each other.

I am trying to compare 2 UIColor(s) to avoid duplication. Each color is referenced in r, g, b, alpha. I form the colors so I can control number formatting.

What would be the appropriate way to handle this?

Answer 1

If you are creating all color the same way you can just use ==.

If your colors are in different color spaces and you just want to compare their RGBA value use the following:

extension UIColor {
    func equals(_ rhs: UIColor) -> Bool {
        var lhsR: CGFloat = 0
        var lhsG: CGFloat = 0
        var lhsB: CGFloat = 0
        var lhsA: CGFloat = 0
        self.getRed(&lhsR, green: &lhsG, blue: &lhsB, alpha: &lhsA)

        var rhsR: CGFloat = 0
        var rhsG: CGFloat = 0
        var rhsB: CGFloat = 0
        var rhsA: CGFloat = 0
        rhs.getRed(&rhsR, green: &rhsG, blue: &rhsB, alpha: &rhsA)

        return  lhsR == rhsR &&
                lhsG == rhsG &&
                lhsB == rhsB &&
                lhsA == rhsA
    }
}

For instance:

let white1 = UIColor.white
let white2 = UIColor(colorLiteralRed: 1, green: 1, blue: 1, alpha: 1)
white1 == white2 //false
white1.cgColor == white2.cgColor //false
white1.equals(white2) //true