When we call postMessage:fromPerson in receiveMessage: we can change our call from:

[self postMessage:[msgComponents objectAtIndex:2]
fromPerson:[msgComponents objectAtIndex:1]];

To:

[self postMessage:[msgComponents [[subArrayWithRange: NSMakeRange(2, [msgComponents length] - 1)] componentsJoinedByString:@":"]] fromPerson:[msgComponents objectAtIndex:1]];

Please double check brackets and that I've constructed that range properly. Granted, this doesn't make for easy reading, but it can be broken up over a couple of lines.