how to change navigationitem title color : <p>I think all day to change the navigation Bar title color, but it doesn't work. this is my code:</p>

<pre><code>var user: User? {
    didSet {
        navigationItem.title = user?.name

         observeMessages()
    }
}
</code></pre>

<p>I use didSet to show the title on the navigation title. </p>
