iOS Swift 3.3 UIColor extension

UIColor.swift

import UIKit

extension UIColor {
    convenience init(hex: String) {
        self.init(hex: hex, alpha:1)
    }
    
    convenience init(hex: String, alpha: CGFloat) {
        let hexWithoutSymbol = hex
        let scanner = Scanner(string: hexWithoutSymbol)
        var hexInt:UInt32 = 0x0
        scanner.scanHexInt32(&hexInt)
        
        var r:UInt32 = 255, g:UInt32 = 255, b:UInt32 = 255
        switch (hexWithoutSymbol.count) {
        case 3: // #RGB
            r = ((hexInt >> 4) & 0xf0 | (hexInt >> 8) & 0x0f)
            g = ((hexInt >> 0) & 0xf0 | (hexInt >> 4) & 0x0f)
            b = ((hexInt << 4) & 0xf0 | hexInt & 0x0f)
            break;
        case 6: // #RRGGBB
            r = (hexInt >> 16) & 0xff
            g = (hexInt >> 8) & 0xff
            b = hexInt & 0xff
            break;
        default:
            printE("UIColor extension error failed convenience init(hex alpha)")
            break
        }
        
        self.init(
            red: (CGFloat(r) / 255),
            green: (CGFloat(g) / 255),
            blue: (CGFloat(b) / 255),
            alpha:alpha)
    }
    
    class func randomFlatColor(index:Int = -1) -> UIColor {
        
        let colors:[(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat)] = [
            (red: 210, green: 77,  blue: 87,  alpha: 1.0),
            (red: 217, green: 30,  blue: 24,  alpha: 1.0),
            (red: 150, green: 40,  blue: 27,  alpha: 1.0),
            (red: 220, green: 198, blue: 224, alpha: 1.0),
            (red: 103, green: 65,  blue: 114, alpha: 1.0),
            (red: 68,  green: 108, blue: 179, alpha: 1.0),
            (red: 210, green: 77,  blue: 87,  alpha: 1.0),
            (red: 228, green: 241, blue: 254, alpha: 1.0),
            (red: 65,  green: 131, blue: 215, alpha: 1.0),
            (red: 89,  green: 171, blue: 227, alpha: 1.0),
            (red: 129, green: 207, blue: 224, alpha: 1.0),
            (red: 82,  green: 179, blue: 217, alpha: 1.0),
            (red: 197, green: 239, blue: 247, alpha: 1.0),
            (red: 34,  green: 167, blue: 240, alpha: 1.0),
            (red: 52,  green: 152, blue: 219, alpha: 1.0),
            (red: 44,  green: 62,  blue: 80,  alpha: 1.0),
            (red: 25,  green: 181, blue: 254, alpha: 1.0),
            (red: 51,  green: 110, blue: 123, alpha: 1.0),
            (red: 34,  green: 49,  blue: 63,  alpha: 1.0),
            (red: 30,  green: 139, blue: 195, alpha: 1.0),
            (red: 58,  green: 83,  blue: 155, alpha: 1.0),
            (red: 52,  green: 73,  blue: 94,  alpha: 1.0),
            (red: 103, green: 128, blue: 159, alpha: 1.0),
            (red: 37,  green: 116, blue: 169, alpha: 1.0),
            (red: 31,  green: 58,  blue: 147, alpha: 1.0),
            (red: 137, green: 196, blue: 244, alpha: 1.0),
            (red: 75,  green: 119, blue: 190, alpha: 1.0),
            (red: 92,  green: 151, blue: 191, alpha: 1.0),
            (red: 78,  green: 205, blue: 196, alpha: 1.0),
            (red: 162, green: 222, blue: 208, alpha: 1.0),
            (red: 135, green: 211, blue: 124, alpha: 1.0),
            (red: 144, green: 198, blue: 149, alpha: 1.0),
            (red: 38,  green: 166, blue: 91,  alpha: 1.0),
            (red: 3,   green: 201, blue: 169, alpha: 1.0),
            (red: 104, green: 195, blue: 163, alpha: 1.0),
            (red: 101, green: 198, blue: 187, alpha: 1.0),
            (red: 27,  green: 188, blue: 155, alpha: 1.0),
            (red: 27,  green: 163, blue: 156, alpha: 1.0),
            (red: 102, green: 204, blue: 153, alpha: 1.0),
            (red: 54,  green: 215, blue: 183, alpha: 1.0),
            (red: 200, green: 247, blue: 197, alpha: 1.0),
            (red: 134, green: 226, blue: 213, alpha: 1.0),
            (red: 46,  green: 204, blue: 113, alpha: 1.0),
            (red: 22,  green: 160, blue: 133, alpha: 1.0),
            (red: 63,  green: 195, blue: 128, alpha: 1.0),
            (red: 1,   green: 152, blue: 117, alpha: 1.0),
            (red: 3,   green: 166, blue: 120, alpha: 1.0),
            (red: 77,  green: 175, blue: 124, alpha: 1.0),
            (red: 42,  green: 187, blue: 155, alpha: 1.0),
            (red: 0,   green: 177, blue: 106, alpha: 1.0),
            (red: 30,  green: 130, blue: 76,  alpha: 1.0),
            (red: 4,   green: 147, blue: 114, alpha: 1.0),
            (red: 38,  green: 194, blue: 129, alpha: 1.0),
            (red: 253, green: 227, blue: 167, alpha: 1.0),
            (red: 248, green: 148, blue: 6,   alpha: 1.0),
            (red: 235, green: 149, blue: 50,  alpha: 1.0),
            (red: 232, green: 126, blue: 4,   alpha: 1.0),
            (red: 244, green: 178, blue: 80,  alpha: 1.0),
            (red: 242, green: 120, blue: 75,  alpha: 1.0),
            (red: 235, green: 151, blue: 78,  alpha: 1.0),
            (red: 254, green: 171, blue: 53,  alpha: 1.0),
            (red: 211, green: 84,  blue: 0,   alpha: 1.0),
            (red: 243, green: 156, blue: 18,  alpha: 1.0),
            (red: 249, green: 105, blue: 14,  alpha: 1.0),
            (red: 249, green: 191, blue: 59,  alpha: 1.0),
            (red: 242, green: 121, blue: 53,  alpha: 1.0),
            (red: 230, green: 126, blue: 34,  alpha: 1.0),
            (red: 236, green: 236, blue: 236, alpha: 1.0),
            (red: 108, green: 122, blue: 137, alpha: 1.0),
            (red: 210, green: 215, blue: 211, alpha: 1.0),
            (red: 238, green: 238, blue: 238, alpha: 1.0),
            (red: 189, green: 195, blue: 199, alpha: 1.0),
            (red: 236, green: 240, blue: 241, alpha: 1.0),
            (red: 149, green: 165, blue: 166, alpha: 1.0),
            (red: 218, green: 223, blue: 225, alpha: 1.0),
            (red: 171, green: 183, blue: 183, alpha: 1.0),
            (red: 242, green: 241, blue: 239, alpha: 1.0),
            (red: 191, green: 191, blue: 191, alpha: 1.0)
        ]
        
        var randomIndex = 0
        if index >= 0 {
            if index < colors.count {
                randomIndex = index
            } else {
                randomIndex = index % (colors.count - 1)
            }
        } else {
            randomIndex = Int(arc4random_uniform(UInt32(colors.count)))
        }
        let randomColor = colors[randomIndex]
        
        return UIColor(
            red: randomColor.red / 255,
            green: randomColor.green / 255,
            blue: randomColor.blue / 255,
            alpha: randomColor.alpha)
    }
}