无法加载 JSON 数据
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【中文标题】无法加载 JSON 数据【英文标题】：Failed To load JSON Data 【发布时间】：2014-04-05 10:15:33 【问题描述】：我正在尝试从 Instagram API 获取 JSON，并使用 Xamarin.ios 将人名放在我的时间轴上以显示在 UITableView 上。我正在尝试使用 JSON.Net 和 Restsharp 来做到这一点，但是在过去的几周里，这个问题从未得到解决。这是我尝试检索数据的方式，问题在于有一条错误消息：System.InvalidCastexception 已被抛出，无法从源类型转换为目标类型。
除此之外，我如何将特定元素加载到表格上？
我已将其更改为JObject.Parse(response.content);
现在我收到这个错误：
这是我更新的代码：
client.ExecuteAsync(request, response =>
var array = JObject.Parse(response.Content);
foreach (JObject obj in array)
var Name = (string)obj["data"]["user"]["full_name"];
var Caption = (string)obj["data"]["caption"]["text"];
var picURL = (string)obj["data"]["images"]["low_resolution"]["url"];
System.Console.WriteLine("Name of " + Name + ", Caption of " + Caption + ", and picurl of " + picURL);
);
这是 JSON 响应：
"pagination":
"next_url": "https://api.instagram.com/v1/users/self/feed?access_token=6489401.88b3fb2.7af2a0355ea24f4590efa1ee82ed0a49&max_id=668439962408115415_16915182",
"next_max_id": "668439962408115415_16915182"
,
"meta":
"code": 200
,
"data": [
"attribution": null,
"tags": [
"selfie"
],
"type": "image",
"location": null,
"comments":
"count": 0,
"data": []
,
"filter": "Normal",
"created_time": "1393953134",
"link": "http://instagram.com/p/lIO1_jmkkr/",
"likes":
"count": 14,
"data": [
"username": "muahjay",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_304620904_75sq_1392618687.jpg",
"id": "304620904",
"full_name": "Jeanettee Nicole Cambero Gamez"
,
"username": "iam_mrsmith31",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_32806209_75sq_1392607367.jpg",
"id": "32806209",
"full_name": "Kiondrix Smith"
,
"username": "anniyalation",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_30752906_75sq_1390523572.jpg",
"id": "30752906",
"full_name": "Niya G."
,
"username": "fonzo_badmon",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_271402803_75sq_1393641486.jpg",
"id": "271402803",
"full_name": "Slimshady"
]
,
"images":
"low_resolution":
"url": "http://distilleryimage11.s3.amazonaws.com/e02592b0a3bf11e3b63212d269f676eb_6.jpg",
"width": 306,
"height": 306
,
"thumbnail":
"url": "http://distilleryimage11.s3.amazonaws.com/e02592b0a3bf11e3b63212d269f676eb_5.jpg",
"width": 150,
"height": 150
,
"standard_resolution":
"url": "http://distilleryimage11.s3.amazonaws.com/e02592b0a3bf11e3b63212d269f676eb_8.jpg",
"width": 640,
"height": 640
,
"users_in_photo": [],
"caption":
"created_time": "1393953134",
"text": "#Selfie",
"from":
"username": "kthompkins7",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_5941681_75sq_1378508674.jpg",
"id": "5941681",
"full_name": "kthompkins7"
,
"id": "668849828018145517"
,
"user_has_liked": false,
"id": "668849827690989867_5941681",
"user":
"username": "kthompkins7",
"website": "",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_5941681_75sq_1378508674.jpg",
"full_name": "kthompkins7",
"bio": "",
"id": "5941681"
,
"attribution": null,
"tags": [
"rp",
"amen"
],
"type": "image",
"location": null,
"comments":
"count": 5,
"data": [
"created_time": "1393949795",
"text": "@tmcmc Dobson a Christian!!!!",
"from":
"username": "keelanwillison",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_26089241_75sq_1380511035.jpg",
"id": "26089241",
"full_name": "Keelanwillison"
,
"id": "668821819276579152"
,
"created_time": "1393950029",
"text": "Yo my cousin got me a signed autograph from you at the Boston boat show thanks man @a_dobson3",
"from":
"username": "danthebigboy914",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_27354625_75sq_1393859632.jpg",
"id": "27354625",
"full_name": "Danny Chiappetta"
,
"id": "668823778033324461"
,
"created_time": "1393950659",
"text": "Amen",
"from":
"username": "sandyrodr",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_44889389_75sq_1361591427.jpg",
"id": "44889389",
"full_name": "sandyrodr"
,
"id": "668829062428545715"
,
"created_time": "1393950664",
"text": "????",
"from":
"username": "cherydaily",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_18483862_75sq_1379884114.jpg",
"id": "18483862",
"full_name": "Andrew \"Drew\" Chery"
,
"id": "668829109488636596"
,
"created_time": "1393951921",
"text": "Amen",
"from":
"username": "bostonsonia",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_182219303_75sq_1391293289.jpg",
"id": "182219303",
"full_name": "Sonia"
,
"id": "668839648625348773"
]
,
"filter": "Normal",
"created_time": "1393949714",
"link": "http://instagram.com/p/lIIUdggtOj/",
"likes":
"count": 324,
"data": [
"username": "bwest05",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_387702554_75sq_1393739891.jpg",
"id": "387702554",
"full_name": "????bb????"
,
"username": "babygirl6193",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_23365060_75sq_1384972330.jpg",
"id": "23365060",
"full_name": "babygirl6193"
,
"username": "derekmooney1",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_218356294_75sq_1388601101.jpg",
"id": "218356294",
"full_name": "Derek Mooney"
,
"username": "zay0613",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_342812999_75sq_1369576584.jpg",
"id": "342812999",
"full_name": "Zay"
]
,
"images":
"low_resolution":
"url": "http://distilleryimage11.s3.amazonaws.com/0e1b270aa3b811e395af12cdc849cb9b_6.jpg",
"width": 306,
"height": 306
,
"thumbnail":
"url": "http://distilleryimage11.s3.amazonaws.com/0e1b270aa3b811e395af12cdc849cb9b_5.jpg",
"width": 150,
"height": 150
,
"standard_resolution":
"url": "http://distilleryimage11.s3.amazonaws.com/0e1b270aa3b811e395af12cdc849cb9b_8.jpg",
"width": 640,
"height": 640
,
"users_in_photo": [],
"caption":
"created_time": "1393949714",
"text": "#RP from @flashgoodwin #AMEN",
"from":
"username": "a_dobson3",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_203045179_75sq_1374262647.jpg",
"id": "203045179",
"full_name": "a_dobson3"
,
"id": "668821135462420769"
,
"user_has_liked": false,
"id": "668821135110099875_203045179",
"user":
"username": "a_dobson3",
"website": "",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_203045179_75sq_1374262647.jpg",
"full_name": "a_dobson3",
"bio": "",
"id": "203045179"
,
"attribution": null,
"tags": [
"tb12"
],
"type": "image",
"location": null,
"comments":
"count": 169,
"data": [
"created_time": "1393952642",
"text": "My guy! The greatest! I just want him to get another ring so the haters can stop saying he hasn't won one since 04. I mean he still won them right? #TomBrady @patriots",
"from":
"username": "k_aus32",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_39840771_75sq_1390431094.jpg",
"id": "39840771",
"full_name": "k_aus32"
,
"id": "668845703585318559"
,
"created_time": "1393952673",
"text": "@heres_jonni9",
"from":
"username": "allyson21lautner",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_184895764_75sq_1393107648.jpg",
"id": "184895764",
"full_name": "Allyson ????"
,
"id": "668845962264823470"
,
"created_time": "1393952694",
"text": "Let's go !",
"from":
"username": "tom12terrific",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_421023272_75sq_1393644166.jpg",
"id": "421023272",
"full_name": "Andrew Estrada"
,
"id": "668846135581853361"
,
"created_time": "1393952856",
"text": "♡",
"from":
"username": "in_neverland74",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_181245582_75sq_1391928288.jpg",
"id": "181245582",
"full_name": "Karen????"
,
"id": "668847491935880949"
,
"created_time": "1393952914",
"text": "Follow for patriots pics daily!! (Ifollowback)",
"from":
"username": "ne_patriots_fanpage__",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_983242248_75sq_1391989748.jpg",
"id": "983242248",
"full_name": "New England Patriots Fanpage"
,
"id": "668847980295472912"
,
"created_time": "1393952952",
"text": "Best ever; period. Let's see anyone win a ring with the humps he's had to work with, (except Randy).",
"from":
"username": "calidoso76",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_1101426299_75sq_1392654362.jpg",
"id": "1101426299",
"full_name": "calidoso76"
,
"id": "668848301545604900"
,
"created_time": "1393953005",
"text": "Shit just because brady hasn't won a ring since 04 don't mean a thing....one more and he'll have 6.....the most superbowl wins than ANY quarterback EVER. @patriots",
"from":
"username": "inkandartsosick",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_260242163_75sq_1363337609.jpg",
"id": "260242163",
"full_name": "Eric Hughes"
,
"id": "668848744304723771"
,
"created_time": "1393953023",
"text": "????????????",
"from":
"username": "bvsed_papi_",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_408657565_75sq_1393905141.jpg",
"id": "408657565",
"full_name": "Abel Valle™"
,
"id": "668848894913791811"
]
,
"filter": "Lo-fi",
"created_time": "1393949267",
"link": "http://instagram.com/p/lIHd-_v8Uj/",
"likes":
"count": 13685,
"data": [
"username": "dollathebarber",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_219503241_75sq_1373905843.jpg",
"id": "219503241",
"full_name": "dollathebarber"
,
"username": "emastro23",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_21122956_75sq_1388823730.jpg",
"id": "21122956",
"full_name": "Eddie Mastrocola"
,
"username": "pat_fan99",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_304601453_75sq_1377084414.jpg",
"id": "304601453",
"full_name": "Timothy Smith"
,
"username": "___adam___q",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_3694047_75sq_1367384028.jpg",
"id": "3694047",
"full_name": "Adam Quinonez"
]
,
"images":
"low_resolution":
"url": "http://distilleryimage10.s3.amazonaws.com/1c67f514a3b711e383121299eef1f922_6.jpg",
"width": 306,
"height": 306
,
"thumbnail":
"url": "http://distilleryimage10.s3.amazonaws.com/1c67f514a3b711e383121299eef1f922_5.jpg",
"width": 150,
"height": 150
,
"standard_resolution":
"url": "http://distilleryimage10.s3.amazonaws.com/1c67f514a3b711e383121299eef1f922_8.jpg",
"width": 640,
"height": 640
,
"users_in_photo": [],
"caption":
"created_time": "1393949267",
"text": "#tb12",
"from":
"username": "patriots",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_1939080_75sq_1385924433.jpg",
"id": "1939080",
"full_name": "New England Patriots"
,
"id": "668817391815214218"
,
"user_has_liked": false,
"id": "668817391496447267_1939080",
"user":
"username": "patriots",
"website": "",
"profile_picture": "http://images.ak.instagram.com/profiles/profile_1939080_75sq_1385924433.jpg",
"full_name": "New England Patriots",
"bio": "",
"id": "1939080"
,
"attribution": null,
"videos":
"low_resolution":
"url": "http://distilleryimage4.s3.amazonaws.com/2cb7114aa3b511e3a3e312f545262070_102.mp4",
"width": 480,
"height": 480
,
"standard_resolution":
"url": "http://distilleryimage4.s3.amazonaws.com/2cb7114aa3b511e3a3e312f545262070_101.mp4",
"width": 640,
"height": 640
]
【问题讨论】：
哪一行抛出异常？ var arr = JsonConvert.DeserializeObject根据您的 JSON 响应（我已从 jsonlint.com 出于验证目的对其进行了更新），似乎 json 数据是对象类型而不是数组类型。因此，在对 JSON 响应进行适当分类后，您更新的代码可能会再次更新，如下所示：
client.ExecuteAsync(request, response =>
RootObject rootObject = JsonConvert.DeserializeObject<RootObject>(response.Content);
foreach (Datum obj in rootObject.data)
var Name = obj.user.full_name;
var Caption = obj.caption.text;
var picURL = obj.images.low_resolution.url;
System.Console.WriteLine("Name of " + Name + ", Caption of " + Caption + ", and picurl of " + picURL);
);
您可能从您的 JSON 响应中派生的类（如下所示）是从 json2csharp.com 生成的
public class RootObject
public Pagination pagination get; set;
public Meta meta get; set;
public List<Datum> data get; set;
public class Datum
public object attribution get; set;
public List<string> tags get; set;
public string type get; set;
public object location get; set;
public Comments comments get; set;
public string filter get; set;
public string created_time get; set;
public string link get; set;
public Likes likes get; set;
public Images images get; set;
public List<object> users_in_photo get; set;
public Caption caption get; set;
public bool user_has_liked get; set;
public string id get; set;
public User user get; set;
public Videos videos get; set;
public class Videos
public LowResolution2 low_resolution get; set;
public StandardResolution2 standard_resolution get; set;
public class StandardResolution2
public string url get; set;
public int width get; set;
public int height get; set;
public class LowResolution2
public string url get; set;
public int width get; set;
public int height get; set;
public class User
public string username get; set;
public string website get; set;
public string profile_picture get; set;
public string full_name get; set;
public string bio get; set;
public string id get; set;
public class Caption
public string created_time get; set;
public string text get; set;
public From from get; set;
public string id get; set;
public class From
public string username get; set;
public string profile_picture get; set;
public string id get; set;
public string full_name get; set;
public class Images
public LowResolution low_resolution get; set;
public Thumbnail thumbnail get; set;
public StandardResolution standard_resolution get; set;
public class StandardResolution
public string url get; set;
public int width get; set;
public int height get; set;
public class Thumbnail
public string url get; set;
public int width get; set;
public int height get; set;
public class LowResolution
public string url get; set;
public int width get; set;
public int height get; set;
public class Likes
public int count get; set;
public List<Datum2> data get; set;
public class Datum2
public string username get; set;
public string profile_picture get; set;
public string id get; set;
public string full_name get; set;
public class Comments
public int count get; set;
public List<object> data get; set;
public class Meta
public int code get; set;
public class Pagination
public string next_url get; set;
public string next_max_id get; set;
【讨论】：
感谢您的帮助！但是最后一件事，我如何将它显示到 UITableView 上？顺便说一句，所有现有代码都可以正常工作。 也欢迎您！很高兴知道它对你有用。顺便说一句，你可以用你的新查询开始一个单独的线程，这样你就可以快速得到你想要的答案。祝你好运！ @Askolein 也欢迎您。您也可以尝试jsonlint 进行 json 验证和缩进格式化。以上是关于无法加载 JSON 数据的主要内容，如果未能解决你的问题，请参考以下文章
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