Cocoa error 3840 using JSON (iOS)

Question

I'm trying to send data to a server and receive the response in JSON format. The problem is that the server has to return "success" or "fail" but it returns "(null)".

Here's the returned 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=XXXXXXXXX {NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}

Is it possible that the error is in the server script?

Here's my function to send the data and receive the response:

- (void) putData:(NSString *)parameter valor:(NSString *)valor {

    NSString *rawString = [NSString stringWithFormat:@"%@=%@", parameter, valor];
    NSData *data = [rawString dataUsingEncoding:NSUTF8StringEncoding];
    NSURL *url = [NSURL URLWithString:@"http://www.xxx.xxx/xxx.php"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    [request setHTTPMethod:@"PUT"];
    [request setHTTPBody:data];
    NSURLResponse *response;
    NSError *error;
    NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
    NSMutableDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
    NSLog(@"responseData: %@ error: %@", json, error);
}

Answer 1

Unless you pass the option NSJSONReadingAllowFragments to [NSJSONSerialization JSONObjectWithData:options:error:] the response from the server must be valid JSON with a top level container which is an array or dictionary.

for example:

    { "response" : "Success" }

PS If you want a mutable dictionary you must also include NSJSONReadingMutableContainers in your options.

Answer 2

It may possible that, the response from your server doesn't contain valid JSON.

Technically, The JSON object must be start with either an "array" or an "object (dictionary)".

So, Whatever your server is returning isn't.

And, you can force the JSON to be consumed regardless by using the NSJSONReadingAllowFragments option.

by using ,

AFJSONResponseSerializer *responseSerializer = [AFJSONResponseSerializer serializerWithReadingOptions:NSJSONReadingAllowFragments];

Answer 3

如果您在iOS设备上连接到VPN，则可能会出现此问题。