Explain the use of below function with meaning in iphone
<p>I m confused to use following methods and i want the clear meaning of all so that i can use that perfectly in my project</p>

<ol>
<li><code>-(void)viewWillAppear</code></li>
<li><code>-(void)viewWillDisappear</code></li>
<li>-<code>(void)viewDidLoad</code></li>
<li><code>-(void)viewDidUnload</code></li>
<li><code>-(void)viewDidAppear</code></li>
<li><code>-(void)viewDidDisappear</code></li>
</ol>

<p>Please can any body who knows these very well then please help me.</p>

<p>Thanks in Advance</p>
