title: Animate CGContextStrokeEllipseInRect
body: <p>I'm trying to animate the drawing of a circle. Something the Shazaam app is doing while recording, but much simpler.<br>
  I've got this code in the drawRect: method to draw the circle:</p>
  
  <pre><code>CGContextRef currentContext = UIGraphicsGetCurrentContext();
  CGContextSetRGBStrokeColor(currentContext, 0.86, 0.86, 0.86, 1.0);
  CGContextSetLineWidth(currentContext, kLineWidth);
  CGContextStrokeEllipseInRect(currentContext, CGRectMake(0.0, 0.0, 150.0, 150.0));
  </code></pre>
  
  <p>I tried to animate the circle with:</p>
  
  <pre><code>[CATransaction begin];
  [CATransaction setValue:[NSNumber numberWithFloat: 3.0f] forKey: kCATransactionAnimationDuration];
  // Drawing code above
  [CATransaction commit];
  </code></pre>
  
  <p>The only thing it does is draw the circle as stated, but it's not animated.</p>
  
  <p>Can anyone help me with this?</p>