                 value = NSNull()
             }
             
-            if customClass == nil || value === NSNull() {
+            if customClass === NSNull() || value === NSNull() {
                 infoDict[key] = value
             } else {
                 let type = NSStringFromClass(value!.classForCoder)

        var c: AnyClass? = cls
        
        // 属性字典
        var infoDict = Dictionary<String, AnyObject?>()
        do {
            // 追加属性字典
            infoDict.merge(modelInfo(c!))

    ///  获取完整模型信息
    ///
    ///  :param: cls 模型类
    func fullModelInfo(cls: AnyClass) -> Dictionary<String, AnyObject> {
        
        if let cache = cacheModel(cls) {
            return cache
