title: registerBackButtonAction , Ionic2 , for different pages
body: <p>I am developing an Ionic2 app. I am confused with <code>registerBackButtonAction</code> functionality.</p>
  
  <p>I have done this on one page (say pageA). and it is working as expected.</p>
  
  <pre><code>this.platform.registerBackButtonAction(() =&gt; {
       console.log("back presed");
      this.abortDownloadAndExit();
      });
  </code></pre>
  
  <p>Now I want to do some other action on <code>registerBackButtonAction</code> on some other page (sayPageB). But Ionic is taking action from <strong>pageA</strong></p>
  
  <p>How can I register different acition on different pages.</p>