         let dic = NSMutableDictionary()
         for (k, v) in self {
             // 第一步序列化key
-            if let k = _serialize(k) as? NSCopying {
+            if let k = _serialize(k) {
                 // 只支持转换为`NSString`
                 guard let k = NSString.deserialize(k) else {
                     continue

            }
        }
        // ok
        return dic
    }
    ///
    /// 反序列化

    /// 序列化
    ///
    public func serialize() -> AnyObject? {
        return NSNumber(unsignedLong: self)
    }
    ///
    /// 反序列化
