在數組中存儲提取的json字典導致nil

我有一個具有諸如url，title和timestamp等屬性的文件的數據庫。當我加載某個視圖控制器時，我正在獲取文件數據並將其加載到tableview中。因爲有多個文件，每個文件都有它們的3個屬性，所以我試圖將數據保存在數組中，然後遍歷數組中的每個對象並提取JSON數據。截至目前，GET請求和響應都是成功的，但該數組仍然爲零。我的方法錯了嗎？在數組中存儲提取的json字典導致nil

let task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in 

     guard let data = data, response = response else 
     { 
      print("No data or response!") 
      return 
     } 

     let strData = NSString(data: data, encoding: NSUTF8StringEncoding) 
     print("Body: \(strData)", terminator: "") 

     do { 
      self.fetchedArray = try NSJSONSerialization.JSONObjectWithData(data, options: .MutableLeaves) as? NSArray 


      print("fetched array count is %i \(self.fetchedArray!.count)") 


      if let jsonArray: NSArray = self.fetchedArray{ 


       for var i = 0; i<jsonArray.count; ++i { 


        let dictResult = jsonArray.objectAtIndex(i) as! NSDictionary 

        let recording = Recordings() 
        recording.trackURL = dictResult["url"] as? String 
        recording.trackTimestamp = dictResult["timestamp"] as? String 
        recording.trackAuthor = dictResult["author"] as? String 
        recording.trackTitle = dictResult["title"] as? String 
        self.recordings?.addObject(recording) 

        } 
      } 
      else 
      { 
       // No error thrown, but not NSDictionary 
       let jsonStr = NSString(data: data, encoding: NSUTF8StringEncoding) 
       print("No error thrown but could not parse JSON: '\(jsonStr)'") 
      } 
     } 
     catch let parseError { 
      // Log the error thrown by `JSONObjectWithData` 
      print(parseError) 
      let jsonStr = NSString(data: data, encoding: NSUTF8StringEncoding) 
      print("Error thrown. could not parse JSON: '\(jsonStr)'") 
     } 
    }) 

    task.resume()

由於現在它的執行倒數第二個else語句print("No error thrown but could not parse JSON: '\(jsonStr)'")，並打印出所有的數據。

數據的日誌序列之前：

Response: <NSHTTPURLResponse: 0x7c349990> { URL: http://127.0.0.1:5000/auth/serve_current_user_files } { status code: 200, headers { 
"Content-Length" = 239; 
"Content-Type" = "application/json"; 
Date = "Sat, 03 Oct 2015 02:53:00 GMT"; 
Server = "Werkzeug/0.10.4 Python/2.7.10"; 
"Set-Cookie" = "session=eyJfZnJlc2giOnRydWUsIl9pZCI6eyIgYiI6Ik16RXhaRGs0TldVM1lUQmxNREJrWlRNeFpqZ3pZMkl3T1dRNE5EZzVPREk9In0sInVzZXJfaWQiOiIxIn0.CPDUjA.Mm56VPuZPIokCZVoRw7X2ySz960; HttpOnly; Path=/"; 
} }Body: Optional({ 
    "recordings": [ 
    { 
    "author": 1, 
    "timestamp": "Sun, 27 Sep 2015 17:44:54 GMT", 
    "title": "Test1.m4a", 
    "url": "/Users/allahesharghi/Desktop/Omid/pythonprojects/sound/sound/uploads/omid1/Test1.m4a" 
} 
]

來源

2015-10-03 Brosef

確保數據是有效的。
在print（「Body：\（strData）」，terminator：「」）它打印出你想要的結果嗎？ – wei

執行的唯一打印語句是在第二個到最後一個else語句之內的打印，因爲該數組是從nil出來的。數據看起來正確。 – Brosef

我的意思是在串行化json對象之前，確保數據是正確的。或者在這裏發佈你的日誌，那將更容易發現錯誤。 – wei

你JSON是：

{ 
    "recordings": [ 
     { 
      "author": 1, 
      "timestamp": "Sun, 27 Sep 2015 17:44:54 GMT", 
      "title": "Test1.m4a", 
      "url": "/Users/allahesharghi/Desktop/Omid/pythonprojects/sound/sound/uploads/omid1/Test1.m4a" 
     } 
    ] 
}

所以，根對象不是數組，它與字典用於陣列的字典鍵recordings。這意味着，當你說

self.fetchedArray = try NSJSONSerialization.JSONObjectWithData(data, options: .MutableLeaves) as? NSArray

self.fetchedArray將是零，因爲低垂到NSArray會失敗，因爲一個NSDictionary不能垂頭喪氣到一個NSArray。

您需要訪問根字典，然後訪問從錄音鍵陣列 -

do { 
     someDictionary = try NSJSONSerialization.JSONObjectWithData(data, options: .MutableLeaves) as? NSDictionary 
     self.fetchedArray = someDictionary!["results"] as? NSArray 
      print("fetched array count is %i \(self.fetchedArray!.count)") 
...

來源

2015-10-03 05:09:37 Paulw11

你說得對。然而，我試着實現這一點，我得到一個錯誤，說：「不能下標值類型的NSDictionary？」當我設置'self.fetchedArray = someDictionary' – Brosef

對不起，我沒有解開可選字典 – Paulw11

在數組中存儲提取的json字典導致nil

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