Easily get RGB, HSL, white, and alpha information, whether a colour is light in Swift. Also can transition between two colours using the float you provide and tell you if a provided colour is lighter or darker.

UIColor+RGBA.swift

//
//  UIColor+RGBA.swift
//
//  Created by Ayden Panhuyzen on 2018-04-10.
//  Copyright © 2018 Ayden Panhuyzen. All rights reserved.
//  https://gist.github.com/aydenp
//

import UIKit

extension UIColor {
    var rgba: (r: CGFloat, g: CGFloat, b: CGFloat, a: CGFloat) {
        var r: CGFloat = 0, g: CGFloat = 0, b: CGFloat = 0, a: CGFloat = 0
        _ = getRed(&r, green: &g, blue: &b, alpha: &a)
        return (r: r, g: g, b: b, a: a)
    }
    
    var hsba: (h: CGFloat, s: CGFloat, b: CGFloat, a: CGFloat) {
        var h: CGFloat = 0, s: CGFloat = 0, b: CGFloat = 0, a: CGFloat = 0
        _ = getHue(&h, saturation: &s, brightness: &b, alpha: &a)
        return (h: h, s: s, b: b, a: a)
    }
    
    var whiteAndAlpha: (white: CGFloat, alpha: CGFloat) {
        var white: CGFloat = 0, alpha: CGFloat = 0
        _ = getWhite(&white, alpha: &alpha)
        return (white: white, alpha: alpha)
    }
    
    func transitioned(to colour2: UIColor, with progress: CGFloat) -> UIColor {
        func tween(value: CGFloat, with value2: CGFloat, progress: CGFloat) -> CGFloat {
            return value + (value2 - value) * progress
        }
        let (r, g, b, a) = rgba, (r2, g2, b2, a2) = colour2.rgba
        return UIColor(red: tween(value: r, with: r2, progress: progress), green: tween(value: g, with: g2, progress: progress), blue: tween(value: b, with: b2, progress: progress), alpha: tween(value: a, with: a2, progress: progress))
    }
    
    var isLight: Bool {
        let (_, _, b, _) = hsba
        return b > 0.5
    }
    
    /// Return the current colour with the alpha multiplied by alphaFactor. Unlike withAlphaComponent(_:), this doesn't just return the colour with the provided alpha, it multiplies the current alpha by your factor (0.5 * 0.5 = 0.25).
    func with(alphaFactor: CGFloat) -> UIColor {
        let (_, alpha) = whiteAndAlpha
        return withAlphaComponent(alpha * alphaFactor)
    }
}