13.范型函数的使用：将字典合并到当前字典

extension Dictionary {
    /// 将字典合并到当前字典
    //字典的分类法， 如果要使用 updateValue 需要明确的指定类型，范型函数
    
    mutating func merge<K, V>(dict: [K: V]) {
        for (k, v) in dict {
            self.updateValue(v as! Value, forKey: k as! Key)
        }
／／

updateValue

    /// Update the value stored in the dictionary for the given key, or, if the

    /// key does not exist, add a new key-value pair to the dictionary.

    ///

    /// Returns the value that was replaced, or `nil` if a new key-value pair

    /// was added.

    }

//取出并且拼接 currentCls 的模型字典

      使用 ： infoDict.merge(modelInfo(currentCls))