title: Draw rectangle in spritekit
body: <p>I'm trying to draw an empty rectangle with a SKShapeNode but does appear on the screen. If i set a color to the fill property the rectangle appears. What could be the issue?</p>
  
  <p>//MyScene.h</p>
  
  <pre><code>#import &lt;SpriteKit/SpriteKit.h&gt;
  @interface MyScene : SKScene
  @end
  </code></pre>
  
  <p>//MyScene.m</p>
  
  <pre><code>#import "MyScene.h"
  
  @implementation MyScene
  
  -(id)initWithSize:(CGSize)size {    
      if (self = [super initWithSize:size]) {
  
          SKShapeNode *shapeNode = [SKShapeNode shapeNodeWithRectOfSize:CGSizeMake(self.frame.size.width/2, self.frame.size.height/2)];
          shapeNode.strokeColor = [SKColor redColor];
          shapeNode.lineWidth = 3;
  
         [self addChild:shapeNode];
      }
      return self;
  }
  
  @end
  </code></pre>