原文：
http://stackoverflow.com/questions/19874935/afnetworking-2-0-post-issue-cocoa-error-3840json-text-did-not-start-with-array
问：
I am attempting to call api.php on my local server(using MAMP). The server side api.php is being called but the content of _POST inside the php code contains the following error:
Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (JSON text did not start with array or object and option to allow fragments not set.) UserInfo=0x15d7bdd0 {NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}
My app that is trying to send the JSON POST request to the api.php is an iOS app using AFNetworking 2
This is my request code:
- (void)postUpdateRequest
{
if (!dataModel)
dataModel = [[DataModel alloc] init];
NSDictionary *params = @{@"foo": @"bar2"};
NSLog(@"%@",params);
/* NSDictionary *params = @{@"cmd":@"update",
@"user_id":[dataModel userId],
@"token":[dataModel deviceToken]
};//@"ip_address":[dataModel getIPAddress]};*/
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
// manager.requestSerializer = [AFJSONRequestSerializer serializer];
[manager POST:ServerApiURL parameters:params success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(@"JSON: %@", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(@"Error: %@", error);
}];
}I looked all over the internet but can't find an answer for my specific problem. No matter what I do I get the same error back.
Why is my JSON not properly formatted? I also can't seem to find a way to sniff what JSON I am actually sending.
Thank you.
答：
When you use the API as in your example, your HTTP message will be composed by using a Content-Type application/x-www-form-urlencoded. Internally, your param dictionary are encoded by AFN (although not strictly correct as specified by w3c), and set as the request body.
Since, you did not specify an Accept header, the server is free to choose the content type for a possible response data (if any).
When you receive a response, you need to always check the HTTP status code and the content type of a response body (if any).
It's likely, the server returned a status code indicating some issue and a response body containing an "error response" in some different kind of content type than you expect (for example, it returned text/html).
有关中文解决方案：
使用AFNetworking 框架 解析数据 报错提示
数据请求失败
Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (JSON text did not start with array or object and option to allow fragments not set.) UserInfo=0x9b7eba0 {NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}
解决：
AFNetWorking的JSON解析默认库是使用的AFJSONRequestOperation模式，只支持text/json，application/json，text/javascript，所以如果出现code=-1016错误则说明当前的JSON解析模式是text/html，所以要加上这段代码：
[AFJSONRequestOperation addAcceptableContentTypes:[NSSet setWithObject:@"text/html"]];//加上这句话
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"%@",kDMBaseURL]];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[AFJSONRequestOperation addAcceptableContentTypes:[NSSet setWithObject:@"text/html"]];//加上这句话
AFJSONRequestOperation *jsonOperation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
DMLog(@"str %@",JSON);
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
DMLog(@"数据请求失败%@",error);
}];
[jsonOperation start];
让他支持text/html模式就可以解决了
数据请求失败
Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (JSON text did not start with array or object and option to allow fragments not set.) UserInfo=0x9ba1b30 {NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}
解决：
后台返回的不是一个有效的JSON string 所以库里面转化的时候一个error就抛出了
就是最后一句说的，肯定是服务器端，在你指定的输出 JSON 数据之前截断输出其他数据，所以出现错误。可以去服务器段判断。