swift md5

extension String  {
    var md5: String! {
        let str = self.cString(using:String.Encoding.utf8)
        let strLen = CUnsignedInt(self.lengthOfBytes(using: String.Encoding.utf8))
        let digestLen = Int(CC_MD5_DIGEST_LENGTH)
        let result = UnsafeMutablePointer.allocate(capacity: digestLen)
        
        CC_MD5(str!, strLen, result)
        
        let hash = NSMutableString()
        for i in 0.. NSString {
        let digestLength = Int(CC_MD5_DIGEST_LENGTH)
        let md5Buffer = UnsafeMutablePointer.allocate(capacity: digestLength)
        CC_MD5(bytes, CC_LONG(length), md5Buffer)
        let output = NSMutableString(capacity: Int(CC_MD5_DIGEST_LENGTH * 2))
        for i in 0..