Freeing objects using ARC

When testing the application that I am developing, I came across this problem, which I would like to discuss. I have a class that should receive a message from the server and must pass the message to the view. Here is how I do it:

- (void) onMessage:(DFTopicMessage *) message {    
    [[NSNotificationCenter defaultCenter] 
     postNotificationName:@"serverMessage" 
     object:message];
}

The class does nothing with the message. When I profile using tools → Leaks, this line of code is marked as a potential leak. I understand that the problem is that the message is highlighted, used, and never released. The first thing that is strange is that I use ARC in my project and therefore expect the OS to release var automatically, but this is obviously not the case (then why doesn't it release var?). In any case, I started thinking how to avoid this leak. Just setting the message to nil, for example in:

- (void) onMessage:(DFTopicMessage *) message {    
    [[NSNotificationCenter defaultCenter] 
     postNotificationName:@"serverMessage" 
     object:message];
      message = nil;
}

. ivar , :

@interface myClass()
@property(nonatomic) DFTopicMessage *message;
@end

@implementation myClass {
@synthetize message;
    ....
   - (void) onMessage:(DFTopicMessage *) msg {
        [self setMessage:msg];

        [[NSNotificationCenter defaultCenter] 
        postNotificationName:@"serverMessage" 
        object:[self message]];

    }
}

, , → . : , var ARC?

!