title: Is a timer mandatory for drawing OPENGL ES
body: <p>I have a method called startAnimation:</p>
  
  <pre><code>-(void)startAnimation{
  1:   self.animationTimer=[NSTimer scheduledTimerWithTimeInterval:1/60
       target:self selector:@selector(gameLoop)
             userInfo:nil repeats:YES];
  2: //[self gameLoop]
  {
  </code></pre>
  
  <p>The gameLoop method is like this:</p>
  
  <pre><code>-(void)gameLoop{
     [self updateModel];
     [self render]
  {
  </code></pre>
  
  <p>Now, a very strange thing happens. If I comment the line 1 and uncomment the line 2 in startAnimation method I will not get the objects rendered to my screen. I thought rendering might require continuously calling the gameLoop metod. But even if I set the timer to not repeat (so repats:NO) objects are drawn. It means calling the gameLoop method just once, but from an NStimer object is enough. But if I call the gameLoop method manually I do not get the objects drawn. I tried calling the method inside a loop which executes 100 times. It did not help either. Is there something special with the timers in regards with OPENGL?Sorry for the question if it's too immature.</p>