Question

I’m having trouble figuring this error out:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** +[NSJSONSerialization writeJSONObject:toStream:options:error:]: Invalid top-level type in JSON write'

Which pertains to this chunk of code (basically I’m creating some JSON and sending it off to a server). I have already checked with the server to see if the socket is opened, which it is!

NSDictionary *blobData = [NSDictionary dictionaryWithObjectsAndKeys:
                          sendString,@"string",
                          nil];
NSString *blobString = [[NSString alloc]
                        initWithData:[NSJSONSerialization dataWithJSONObject:blobData options:kNilOptions error:&error]
                        encoding:NSUTF8StringEncoding];
NSLog(@"Blob Created: %@", blobString);
NSDictionary *requestData = [NSDictionary dictionaryWithObjectsAndKeys:
                             @"send_string",@"request_type",
                             [NSNumber numberWithInt:0],@"security_level",
                             @"ios",@"device_type",
                             //No Email Provided, This is just for testing
                             blobData,@"blob",
                             nil];

NSData *JSONRequestData = NULL;
if ([NSJSONSerialization isValidJSONObject:requestData]) {
    NSLog(@"Proper JSON Object");
    JSONRequestData = [NSJSONSerialization dataWithJSONObject:requestData options:kNilOptions error:&error];
}
else {
    NSLog(@"requestData was not a proper JSON object");
    return FALSE;
}
NSLog(@"Error:%@",[[error userInfo] objectForKey:@"NSDebugDescription"]);
NSLog(@"Contents of JSONRequestData: %@",[[NSString alloc] initWithData:JSONRequestData encoding:NSUTF8StringEncoding]);
[NSJSONSerialization writeJSONObject:JSONRequestData toStream:outputStream options:0 error:&error];

Am I creating the JSON object wrong? Maybe there’s a problem with the way I’m handling the “blob”

Here’s what the NSLogs prints after I’ve created JSONRequestData

{"security_level":"0","request_type":"send_string","device_type":"ios","blob":{"string":"hello"}}

Answer 1

writeJSONObject expects the actual unserialized object you want to send, so in this case you’d want to pass it the requestData object, not JSONRequestData like:

NSJSONSerialization writeJSONObject:requestData toStream:outputStream options:0 error:&error];