Type-check: How to check if NSData is an NSArray?

Question

I'm currently working with the Multipeer Connectivity Framework in XCode for an iPad App.

I want to send messages with the framework (NSStrings, Booleans & NSArrays) and Strings are working fine, but I need some sort of type-check to convert the NSData object into a String, Array, etc.

This is what my didReceiveData methode looks like:

- (void)session:(MCSession *)session didReceiveData:(NSData *)data fromPeer:(MCPeerID *)peerID{

    NSString *message = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

    NSMutableArray *recievedArray = [NSKeyedUnarchiver unarchiveObjectWithData:data];

    if ([message isEqualToString:@"PeerIsConnected"]) {
        NSLog(@"Peer sended: Connected!");
        self.connectionIsOn = TRUE;
        dispatch_async(dispatch_get_main_queue(),^{
            [self changeConnectionButton:TRUE];
        });

        NSLog(@"Connection is on (data received) : %@", (self.connectionIsOn) ? @"YES" : @"NO");
    }

    if ([message isEqualToString:@"Disconnect"]) {
        NSLog(@"Peer sended: Disconnect!");
        self.connectionIsOn = FALSE;
        dispatch_async(dispatch_get_main_queue(),^{
            [self changeConnectionButton:FALSE];
        });
    }


    if ([message isEqualToString:@"GoWasClicked"]) {

        self.muliplayergameIsOn = TRUE;
        self.myTurn = TRUE;

        self.startDate = [NSDate date];
        self.stopWatchTimer = [NSTimer scheduledTimerWithTimeInterval:1.0/10.0
                                                               target:self
                                                             selector:@selector(updateTimer)
                                                             userInfo:nil
                                                              repeats:YES];
}

I need some if case so I can cast the NSData object into a NSString OR NSArray OR etc.

How can I solve this problem?

Thanks in advance!

EDIT: This is how the Array is sended:

- (void) sendArray:(NSMutableArray *) arrayToSend{

    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:arrayToSend];

    NSError *error;
    [self.mySession sendData:data toPeers:[self.mySession connectedPeers] withMode:MCSessionSendDataUnreliable error:&error];

}

Answer 1

You could use NSKeyedArchiver for all kinds of objects that you send (string, array, ...). Then you can check on the receiving side with

id receivedObject = [NSKeyedUnarchiver unarchiveObjectWithData:data];
if ([receivedObject isKindOfClass:[NSArray class]]) {
    NSArray *receivedArray = receivedObject;
    // handle array ...

} else if ([receivedObject isKindOfClass:[NSString class]]) {
    NSString *receivedString = receivedObject;
    // handle string ...
}