title: iPhone CALayer animation
body: <p>I am drawing a line animation, connecting 2 points with a line.  This is my code:</p>
  
  <pre><code>-(void) drawObject{     
      rootLayer   = [CALayer layer];
      rootLayer.frame = self.view.bounds;
      [self.view.layer addSublayer:rootLayer];
  
      lineStartPath = CGPathCreateMutable();
      CGPathMoveToPoint(lineStartPath, nil, 160, 50);
      CGPathAddLineToPoint(lineStartPath, nil, 160, 50);
      CGPathCloseSubpath(lineStartPath);
  
      lineEndPath = CGPathCreateMutable();
      CGPathMoveToPoint(lineEndPath, nil, 160, 50);
      CGPathAddLineToPoint(lineEndPath, nil, 160, 300);
      CGPathCloseSubpath(lineEndPath);
  
      shapeLayer = [CAShapeLayer layer];
      shapeLayer.path = lineStartPath;
      UIColor *strokeColor = [UIColor colorWithHue:0.557 saturation:0.55 brightness:0.96 alpha:1.0];
      shapeLayer.strokeColor = strokeColor.CGColor;
      shapeLayer.lineWidth = 3.0;
  
      [rootLayer addSublayer:shapeLayer];
  
      [self performSelector:@selector(startAnimation) withObject:nil afterDelay:1.0];
  }
  
  -(void) startAnimation{
      CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"path"];
      animation.duration = 0.5;
      animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
      animation.fromValue = (id)lineStartPath;
      animation.toValue = (id)lineEndPath;
      [shapeLayer addAnimation:animation forKey:@"animatePath"];
  }
  </code></pre>
  
  <p>The weak point is after the animation is ended, the line disappears. I want that after my line is drawn between those 2 points, id does not disappear. Give me a hint please.</p>