How to hide button after click
<p>I create <code>Start_button</code> and make <code>@IBOutlet</code> and <code>@IBAction</code></p>

<pre><code>@IBOutlet weak var Start_button: UIButton!

@IBAction func Start_button(sender: AnyObject)
</code></pre>

<p>Now, i want hide button after click. I try this, but this don't work:</p>

<pre><code>@IBAction func Start_button(sender: AnyObject)
    {
        Start_button.hidden = true;
    }
</code></pre>

<p>Error message:</p>

<pre><code>fatal error: unexpectedly found nil while unwrapping an Optional value
(lldb) 
</code></pre>

<p>How i can hide this button?</p>

<p>Thanks for helping!</p>