title: typedef NS_OPTIONS check like UIViewAutoresizing
body: <p><em>A short introduction to what I want to achieve with this:</em>
  <br>I've a custom <code>UIView</code> where I want to make arrows visible, for example on bottom and left side.
  I thought it would be possible to do this the same way as <code>UIViewAutoresizing</code> does it.</p>
  
  <p>So I created a similar <code>typedef</code> for my custom view:</p>
  
  <pre><code>typedef NS_OPTIONS(NSUInteger, Arrows) {
      ArrowNone      = 0,
      ArrowRight     = 1 &lt;&lt; 0,
      ArrowBottom    = 1 &lt;&lt; 1,
      ArrowLeft      = 1 &lt;&lt; 2,
      ArrowTop       = 1 &lt;&lt; 3
  };
  </code></pre>
  
  <p>Also in my custom view header file, I added:</p>
  
  <pre><code>@property (nonatomic) Arrows arrows;
  </code></pre>
  
  <p>This all works and now I'm able to set the property:
  <br><code>customview.arrows = (ArrowBottom | ArrowLeft);</code></p>
  
  <p>This returns <code>6</code>.</p>
  
  <p>Now's my question, how can check if my <code>arrows</code> property contains bottom and left?
  I tried:</p>
  
  <pre><code>if (self.arrows == ArrowLeft) {
      NSLog(@"Show arrow left");
  }
  </code></pre>
  
  <p>This didn't do anything. Is there another way to check this?</p>