NSTimer to update label
<pre><code>self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(updateTimerDisplay) userInfo:nil repeats:YES];
[runLoop addTimer:self.timer forMode:NSRunLoopCommonModes];
</code></pre>

<p>This code-snippet is copied from my viewDidLoad method, so it is runned from the main-thread. All it do is to call a method to update a label. </p>

<p>I thought I need to have a own thread for doing this, but after getting help on this at SO I figured out that I did not. </p>

<p>However, I do not understand the <code>NSRunLoopCommonModes</code>. Why does it work?</p>

<hr>

<p>AND the timer updates the label which is a "digital counter" which is on the same screen as a tableview so it CAN'T stop the timer even if the user holds the screen.</p>

<p>Thanks.</p>
