title: add subLayer to a imageView.layer
body: <p>well I know that every imageViews have a layer (we can access it with :imageView.layer).I would like to use the layer of my <code>imageView</code> and add a subLayer to it's layer:<code>shapeLayer</code>(that is a CAShapeLayer) My code doesn't work, it doesn't show the shape layer!</p>
  
  <pre><code>- (void)viewDidLoad 
  {
     imageView = [[UIImageView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
     [self.view addSubview:imageView];
  }
  
  - (void)anotherMethod
  {
     [imageView.layer addSublayer:shapeLayer];
  }
  </code></pre>
  
  <p>How can I solve this please ? </p>