Invalid type in JSON write (NSConcreteData)?

Question

I am using AFNetworking to post an audio with some data. I am getting following exception.

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Invalid type in JSON write (NSConcreteData)'

I am using this code..

dict=@{@"access_token":[defaults valueForKey:@"TOKEN"],@"email":email,@"prayer":passData};

if ([NSJSONSerialization isValidJSONObject:dict]) {
        NSLog(@"Proper JSON Object");

    }
    NSError *error;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dict options:NSJSONWritingPrettyPrinted error:&error];

    NSURL *URL = [NSURL URLWithString:url];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL
                                                           cachePolicy:NSURLRequestReloadIgnoringCacheData  timeoutInterval:10];

    [request setHTTPMethod:@"POST"];
    [request setValue: @"application/json" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:jsonData];
 AFHTTPRequestOperation *op = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    op.responseSerializer = [AFJSONResponseSerializer serializerWithReadingOptions:NSJSONReadingAllowFragments];
    [op setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {}

I need to post values in this format

{
    "access_token" = 2cf0d8a66654fa4f;
    email = "";
    prayer =     {
        audio = <63616666 00010000 64657363 00000000 00000020 40e58880 00000000 696d6134 00000000 00000044 00000040 00000002 00000000 6b756b69 00000000 00000000 66726565 0000000>
 98903013 31faae9c bb7b0780 80808080>;
        "category_id" = "";
        description = "";
        "expired_date" = "Expiration Date";
        "is_audio" = 1;
        "is_urgent" = 0;
        "prayer_access_id" = "";
        "prayer_type_id" = 1;
        subject = "";
    };
}

I don't know why this is happening, I have posted values before with this format but when I try to post audio as data, I am getting this exception. Thanks in advance

Edit

Here i am making data

 NSData *audioFile=[self audioData];
 if (audioFile==nil) {
        [passData setObject:@"" forKey:@"audio"];
        [passData setObject:@"0" forKey:@"is_audio"];

    }else{

        [passData setObject:audioFile forKey:@"audio"];
        [passData setObject:@"1" forKey:@"is_audio"];
    }


-(NSData *)audioData{
    NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(
                                                            NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *docsDir = [dirPaths objectAtIndex:0];
    NSString *soundFilePath = [docsDir
                               stringByAppendingPathComponent:@"recordTest.caf"];

    NSURL *url = [NSURL fileURLWithPath:soundFilePath];
    NSData *audioData=[NSData dataWithContentsOfURL:url];
    return audioData;
}

this what i am inserting audio file

Answer 1

The problem is that you cannot put NSData in JSON. The audio is NSData. As the NSJSONSerialization documentation says:

An object that may be converted to JSON must have the following properties:

• The top level object is an NSArray or NSDictionary.

• All objects are instances of NSString, NSNumber, NSArray, NSDictionary, or NSNull.

• All dictionary keys are instances of NSString.

• Numbers are not NaN or infinity.

If you want to include NSData in JSON, you have to convert it to a string. The common way to do that is to base64 encode it (and then, in the destination, decode the base64 string).