swift3.0把#ffffff或者ffffff格式转为UIColor的方法

extension UIColor {

    

    // MARK:- 把#ffffff颜色转为UIColor

   class
func colorWithHexString(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)
{

            returnUIColor.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)

        

        returnUIColor(red:
CGFloat(r) /255.0, green:
CGFloat(g) /255.0, blue:
CGFloat(b) /255.0, alpha:
CGFloat(1))

    }

}