Update UILabel from another class
===

I was looking for something that solve my problem, but I didn't find anything usefull.
Some code:
<code>ClassA.h</code>

    #import "ClassB.h"

    @interface ClassA : UIViewController
    {
       ClassB *clsB;
    }

    @property (retain, nonatomic) IBOutlet UILabel  *label;
    @property (retain, nonatomic) ClassB *clsB;

<code>ClassA.m</code>

    @implamentation ClassA
    @synthesize label, clsB;

    - (void)viewDidLoad
    {
       ...
       clsB = [[ClassB alloc] init];
       label.text = [[NSString stringWithFormat:@"%f", clsB.var];
       ...
    }
    

The problem is that <code>var</code> is changing (I check this in ClassB implementation with NSLog) but those changes don't affect the <code>label.text</code>.

I've already tried to import <code>ClassA</code> in <code>ClassB</code> too, but this didn't work (import error) either. I've heard something about notification center but I've never used it before.

So, is there another way to do that?
Thanks