在RestKit RKObjectMapping json中包含样式

Question

当我在swift中用RestKit RKObjectMapping映射下面的嵌套json时，它将返回错误。因为extra有style。如果extra除了style，它就没问题了。风格是保留字？
我该如何解决？感谢。

{
    "sucess": true,
    "error": {
        "code": "",
        "message": ""
    },
    "data": [
        {
            "id": 1,
            "name": "test",
            "extra": {
                "style": 1
            }
        }
    ]
}

映射代码。

class func responseMapping() -> RKObjectMapping {
    let objectMapping = RKObjectMapping(forClass: self)
    objectMapping.addAttributeMappingsFromDictionary([
        "id": "id",
        "name": "name",
        "extra": "extra"
    ])

    return objectMapping
}

我正在使用这个。

RKObjectManager.sharedManager().getObject(self,
    path: path,
    parameters: params,
    success: { (operation: RKObjectRequestOperation!, result: RKMappingResult!) -> Void in
            completionHandler(Result(result.array() as! [Content]))
    }) { (operation: RKObjectRequestOperation!, error: NSError!) -> Void in
            completionHandler(Result(error))
}