Sending data error?

typedef struct _protocol1
{
    int type;
    CGPoint pos;
} Protocol1;

-(void)sendData {
    NSError *error;
    Protocol1 msg;
    msg.pos = ccp(100,100);
    msg.type = 1;
    NSData *packet = [NSData dataWithBytes:&msg length:sizeof(Protocol1)];
    [self.myMatch sendDataToAllPlayers: packet withDataMode: GKMatchSendDataReliable error:&error];
    if (error != nil)
    {
        NSLog(@"error"]);
    }
}

That is a chunk of code from my project. And I'm gett开发者_StackOverflow中文版ing an error. However, I am unsure how to retrieve more information to help me debug. Can someone help me?

Sorry, I'm quite new with iOS development...

Using Cocos2d for a game.

EDIT

I am using the Simulator and my iPhone to test this. I doubt that is the problem, I already got the match working and everything...

To print out your error, try this!

NSLog(@"here is the error material:  %@", [error localizedDescription])

if you have trouble, just click on NSError in your XCode4.

Then look at the right column, and click to get to the documentation.

(Or just search "NSError" in the Xcode documentation.)

Bring up "NSError Class Reference". It is very simple.

Be sure to look at the VARIOUS EXAMPLE CODE given.

For example scroll down to "localizedDescription" ad see the three sample codes. ("LazyTableImages, SeismicXML, URLCache")

You can download and look at the example projects. Search on "localizedDescription" and you'll see examples, if you're having trouble!

If you teach a man to fish ... Lol have fun.