difference among NSthread and NStimer and NSNotifcation?
<p>What is the difference among following codes</p>

<p>1) </p>

<pre><code> [NSThread detachNewThreadSelector:@selector(myFunction) toTarget:self withObject:thename];
</code></pre>

<p>2)</p>

<pre><code>[NSTimer scheduledTimerWithTimeInterval:1.0
                                 target:self 
                               selector:@selector(myFunction:) 
                               userInfo:nil 
                                repeats:NO];
</code></pre>

<p>3)</p>

<pre><code>[self performSelector:@selector(myFunction) withObject:nil afterDelay:myDelay]; 
</code></pre>

<p>4)    </p>

<pre><code> [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(myFunction:) name:thename object:nil];
</code></pre>
