Ios 错误域=NSCOCAERRORDOMAIN代码=3840“；操作无法’；不可能完成

我试图得到json api的响应，但我在代码中发现了这种类型的错误，所以，请帮助我解决这个问题

错误：错误域=NSCOCAERRORDOMAIN代码=3840“操作 无法完成。（Cocoa错误3840。）（JSON文本未启动 使用数组或对象，并选择允许不设置片段。） UserInfo=0x7fed834422c0{NSDebugDescription=JSON文本未启动 具有数组或对象，并具有允许不设置片段的选项。， NSUnderlyingError=0x7fed837c2790“请求失败：内部服务器 错误（500）“}

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从错误消息中，从webservice返回的数据不是正确的json格式。你可以发布来自web服务的数据吗？是的，我将发布数据JSON:{feed=（{“comment_count=”；“like_count=”；“like_type=”；“post_datetime”=“2015-11-14 12:02:41”；“post_heading”=Maruti；“post_id”=656；“post_image”=“4640321965.png”；“post_status”=A；“post_type”=0；“user_fname”=Kush；“user_id”=38；“user_lname”=“Ghodasara CMT，CFP”；“user_profile”=“7868630525.jpg”；）正在查看您的代码..等待，谢谢

 AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    manager.responseSerializer.acceptableContentTypes = [NSSet setWithObject:@"text/html"];
    NSMutableDictionary *params = [NSMutableDictionary dictionary];
    [params setValue:[[NSUserDefaults standardUserDefaults] objectForKey:@"UID"] forKey:@"user_id"];
    [params setValue:self.strPostID forKey:@"post_id"];

    [manager POST:[NSString stringWithFormat:@"%@webservices/post/loaddetails", API_URL] parameters:params success:^(AFHTTPRequestOperation *operation, id responseObject)
     {
         NSLog(@"JSON: %@", [[responseObject objectForKey:@"feed"] objectAtIndex:0]);
         NSDictionary *dict = [[responseObject objectForKey:@"feed"] objectAtIndex:0];

         if (![[dict objectForKey:@"post_image"] isEqualToString:@""])
         {
             NSArray *arrTemp = [[dict objectForKey:@"post_image"] componentsSeparatedByString:@"."];
             if ([[arrTemp objectAtIndex:1] isEqualToString:@"gif"])
             {

                 [controller setInitialText:@"Hi,"];
                 //[controller addURL:[NSURL URLWithString:imgViewPost.imageURL]];
                 // [controller addImage:[UIImage imageNamed:@"socialsharing-facebook-image.jpg"]];
                 [controller addImage:[UIImage animatedImageWithAnimatedGIFURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@images/postimage/%@",API_URL,[dict objectForKey:@"post_image"]]]]];
                 [self presentViewController:controller animated:YES completion:Nil];

             }
             else
             {

                 [controller setInitialText:@"First post from my iPhone app"];
                 //[controller addURL:[NSURL URLWithString:imgViewPost.imageURL]];
                 // [controller addImage:[UIImage imageNamed:@"socialsharing-facebook-image.jpg"]];
                 [controller addURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@images/postimage/%@",API_URL,[dict objectForKey:@"post_image"]]]];
                 [self presentViewController:controller animated:YES completion:Nil];
             }
         }


         dict = nil;
         [[AppDelegate sharedAppDelegate] hideProgress];
     } failure:^(AFHTTPRequestOperation *operation, NSError *error)
     {
         [[AppDelegate sharedAppDelegate] hideProgress];
         NSLog(@"Error: %@", error);
         UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"" message:[error localizedDescription] delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
         [alert show];
         alert = nil;
     }];