Swift3 swift |未解决的标识符错误

代码如下：

let task: URLSessionDataTask = session.dataTask(with: request as URLRequest) { (data, response, error) -> Void in
     // Get the HTTP status code of the request.
        let statusCode = (response as! HTTPURLResponse).statusCode
        if statusCode == 200 {
            // Convert the received JSON data into a dictionary.
            do {
                if let dataDictionary = (try? JSONSerialization.jsonObject(with: data!, options: [JSONSerialization.ReadingOptions.mutableContainers])) as? [String:Any] { let accessToken = dataDictionary["access_token"] as? String }

                UserDefaults.setObject(accessToken, forKey: "LIAccessToken")
                UserDefaults.standard.synchronize()

                DispatchQueue.main.async(execute: { () -> Void in
                    self.dismiss(animated: true, completion: nil)
                    })
            }
            catch {
                print("Could not convert JSON data into a dictionary.")
            }
        }

新代码：这是来自应用程序尾码，无法在最新的swift中编译

让dataDictionary=尝试NSJSONSerialization.JSONObjectWithDatadata！，选项：NSJSONReadingOptions.MutableContainers

                let accessToken = dataDictionary["access_token"] as! String

                NSUserDefaults.standardUserDefaults().setObject(accessToken, forKey: "LIAccessToken")
                NSUserDefaults.standardUserDefaults().synchronize()

                dispatch_async(dispatch_get_main_queue(), { () -> Void in
                    self.dismissViewControllerAnimated(true, completion: nil)
                })

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您必须这样使用：

您在if循环中定义了accessToken。而你正在它之外访问它

if let dataDictionary = (try? JSONSerialization.jsonObject(with: data!, options: [JSONSerialization.ReadingOptions.mutableContainers])) as? [String:Any] { 
    let accessToken = dataDictionary["access_token"] as? String 
    UserDefaults.setObject(accessToken, forKey: "LIAccessToken")
}

---

未解析的标识符accessToken。。。当我在外部定义它时，我会在哪一行得到更多的错误？这只是因为编译器不知道什么是accesToken！请参阅了解是什么，这是程序员的一个基本概念，您离不开它。我正在尝试从appcoda编译该类：这带来了其他错误：实例成员“setObject”不能用于类型“UserDefaults”；你的意思是使用这种类型的值吗？-如何去掉它？