title: Assigning to 'readonly' return result not allowed, but property is declared "readwrite"
body: <p>I have a class with <code>readwrite</code> <code>int</code> properties:</p>
  
  <pre><code>@interface PlayScene : UIView
  
  @property (readwrite, assign) int Figure1;
  @property (readwrite, assign) int Figure2;
  @property (readwrite, assign) int Figure3;
  </code></pre>
  
  <p>But when I try to change the value of the properties, an error occurs: </p>
  
  <pre><code>[self Figure1] = 1;
  </code></pre>
  
  <blockquote>
    <p>assigning to 'readonly' return result of an Objective-C message not allowed</p>
  </blockquote>
  
  <p>What is the problem?</p>