ios - JSON 解析数据未被调用？ swift

Question

我已经从 API 解析了我的数据，但是当我尝试从解析的 NSDictionary 数据中设置一些值时，没有调用 println 语句。它发生在带有“用户”键的字典中，我尝试在其中设置学生的名字和姓氏。

func getUserData(hostViewController: UIViewController ) {
        if self.userID == nil{
            println("User ID is nil")
        }
        else {
        var key = self.userID
        let urlString = UdacityClient.Constants.BaseURLSecure + "/users" + "/\(key)"
        println(urlString)
        let url = NSURL(string: urlString.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)!)
        let request = NSMutableURLRequest(URL: url!)


        let task = session.dataTaskWithRequest(request) {data, response, error in
            if error != nil {
                dispatch_async(dispatch_get_main_queue(), { () -> Void in
                    println(error)
                    let alertController = UIAlertController(title: "Oh no", message: "Error in User Data", preferredStyle: UIAlertControllerStyle.Alert)

                    let cancelAction = UIAlertAction(title: "Retry", style: UIAlertActionStyle.Default, handler: { (alert) -> Void in
                        hostViewController.dismissViewControllerAnimated(true, completion: nil)
                    })
                    alertController.addAction(cancelAction)

                    hostViewController.presentViewController(alertController, animated: true, completion: nil)
                })

                println("Error in User Data")

            }  else {
                let newData = data.subdataWithRange(NSMakeRange(5, data.length - 5))
                var parsingError: NSError? = nil
                let parsedResult = NSJSONSerialization.JSONObjectWithData(newData, options: NSJSONReadingOptions.AllowFragments, error: &parsingError) as! NSDictionary


                if let userDictionary = parsedResult["user"] as? [String: AnyObject] {
                    if let firstName = userDictionary["first_name"] as? String {
                        self.firstName = firstName
                        println("This is not printing ")
                        println(firstName)
                    }
                }

                if let userDictionary = parsedResult["user"] as? [String: AnyObject] {
                    if let lastName = userDictionary["last_name"] as? String {
                        self.lastName = lastName
                        println("This is not printing also")
                        println(lastName)
                    }
                }

                if let err = parsingError {
                    dispatch_async(dispatch_get_main_queue(),{ () -> Void in
                        println(err)
                        let alertController = UIAlertController(title: "Oh no", message: "Error in Parsing User Data from Udacity", preferredStyle: UIAlertControllerStyle.Alert)

                        let cancelAction = UIAlertAction(title: "Retry", style: UIAlertActionStyle.Default, handler: { (alert) -> Void in
                            hostViewController.dismissViewControllerAnimated(true, completion: nil)
                        })
                        alertController.addAction(cancelAction)

                        hostViewController.presentViewController(alertController, animated: true, completion: nil)
                    })

                }


            }
            }


        task.resume()
        }
    }

我的请求 URL:

https://www.udacity.com/api/users/Optional("3778758647")

我的 ResponseKeys 结构:

struct JSONResponseKeys {
        //getSessionID
        static let Status = "status"
        static let Account = "account"
        static let Key = "key"
        static let Session = "session"
        static let ID = "id"

        //getUserData
        static let User = "user"
        static let FirstName = "first_name"
        static let LastName = "last_name"


    }

当我在下面的客户端中调用学生的名字和姓氏时，在展开可选值时发生 fatal error :

UdacityClient.sharedInstance().firstName!) and      UdacityClient.sharedInstance().lastName!

JSON 解析结果控制台日志:

 {
    error = "Parameter 'user_key' key contains unescaped special character '\"': 'Optional(\"3778758647\")'";
    parameter = "user_key";
    status = 400;
}

Answer 1

我看起来你的主要错误来自于 userID 是一个需要解包的可选值这一事实。这就是你看到的原因

https://www.udacity.com/api/users/Optional("3778758647")代替https://www.udacity.com/api/users/3778758647 和您的服务器错误说的是同一件事。

试试这个基本大纲，而不是:

if self.userID == nil {
   ...
}

你可以使用 guard 语句提前返回，像这样:

guard let userID = self.userID as? String else { return }

这样做的好处是还可以展开您的值(value)，摆脱 "Optional()"

另一种方法是使用:

if let userID = self.userID as? String {
    ...
}