Advanced color literals

Colors.swift

import Fx
import UIKit

public struct RGBA {
	var r: UInt8
	var g: UInt8
	var b: UInt8
	var a: UInt8
}

public extension UIColor {

	convenience init(_ value: RGBA) {
		self.init(
			red: CGFloat(value.r) / 255,
			green: CGFloat(value.g) / 255,
			blue: CGFloat(value.b) / 255,
			alpha: CGFloat(value.a) / 255
		)
	}

	convenience init(light: RGBA, dark: RGBA) {
		let lightColor = UIColor(light)
		let darkColor = UIColor(dark)
		self.init(dynamicProvider: { traits in
			traits.userInterfaceStyle == .dark ? darkColor : lightColor
		})
	}

	var light: UIColor {
		return resolvedColor(with: UITraitCollection(userInterfaceStyle: .light))
	}
	var dark: UIColor {
		return resolvedColor(with: UITraitCollection(userInterfaceStyle: .dark))
	}

	var rgba: RGBA {
		var red = 0 as CGFloat
		var green = 0 as CGFloat
		var blue = 0 as CGFloat
		var alpha = 0 as CGFloat

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

		return RGBA(
			r: UInt8(red * 255),
			g: UInt8(green * 255),
			b: UInt8(blue * 255),
			a: UInt8(alpha * 255)
		)
	}

	var rgbHex: Int {
		let rgba = self.rgba
		return Int(rgba.r) << 16 | Int(rgba.g) << 8 | Int(rgba.b)
	}

	var rgbHexString: String { return String(format: "%06x", rgbHex) }
}

extension RGBA: ExpressibleByIntegerLiteral {
	public init(integerLiteral value: Int) {
		let byte = { idx in UInt8((value & (0xFF << (8 * idx))) >> (8 * idx)) }
		self = RGBA(r: byte(2), g: byte(1), b: byte(0), a: 255)
	}
}

func * (rgba: RGBA, alpha: CGFloat) -> RGBA {
	return modify(rgba) { $0.a = UInt8(CGFloat($0.a) * alpha.clamped(to: 0...1)) }
}

Usage:

public extension UIColor {
	static let textSecondary = UIColor(light: 0x9A938D, dark: 0xFFFFFF * 0.6)
}