Swift中使用16进制颜色 HexString

import UIKit

//swift中是用extension来进行拓展
extension UIColor{
    // MARK:- 把#ffffff颜色转为UIColor
    class func color(hex:String)->UIColor{
        var cString = hex.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines).uppercased()
        if (cString.hasPrefix("#")) {
            let index = cString.index(cString.startIndex, offsetBy:1)
            cString = cString.substring(from: index)
        }

        if (cString.characters.count != 6) {
            return UIColor.red
        }

        let rIndex = cString.index(cString.startIndex, offsetBy: 2)
        let rString = cString.substring(to: rIndex)
        let otherString = cString.substring(from: rIndex)
        let gIndex = otherString.index(otherString.startIndex, offsetBy: 2)
        let gString = otherString.substring(to: gIndex)
        let bIndex = cString.index(cString.endIndex, offsetBy: -2)
        let bString = cString.substring(from: bIndex)

        var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;
        Scanner(string: rString).scanHexInt32(&r)
        Scanner(string: gString).scanHexInt32(&g)
        Scanner(string: bString).scanHexInt32(&b)

        return UIColor(red: CGFloat(r) / 255.0, green: CGFloat(g) / 255.0, blue: CGFloat(b) / 255.0, alpha: CGFloat(1))
    }

    // MARK:- 把#ffffff颜色转为UIImage
    class func creatImageWithColor(color: UIColor) -> UIImage {
        let rect = CGRect(x: 0.0, y: 0.0, width: 1.0, height: 1.0)
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()
        context!.setFillColor(color.cgColor)
        context!.fill(rect)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image!
    }

}