title: How to refer each UIButton
body: <p>I add 10 buttons to UIScrollView</p>
  
  <pre><code>for (int i=0; i&lt;10; i++) {
  
       UIButton *btn =  ....  
  
       [ScrollView addSubview:btn];
  
  }
  </code></pre>
  
  <p>How can i refer to each button ? </p>