title: Ionic v4 - how do I autofocus on a Input?
body: <p>I have a view with an input <code>&lt;ion-input #codigobarras&gt;&lt;/ion-input&gt;</code></p>
  <p>How can I auto focus on this input?</p>
  <h1>What have I tried</h1>
  <pre><code>@ViewChild('codigobarras') input_codigobarras: Input;
  
  ...
  
  ionViewDidEnter() {
      this.input_codigobarras.focus(); // didn't work = temp2.focus is not a function
      this.input_codigobarras.focus.emit(); // didn't work = do nothing, just returns undefined
      this.input_codigobarras.getElementRef().nativeElement.focus() // didn't work = do nothing, just returns undefined
      this.input_codigobarras.setFocus(); // didn't work = do nothing, just returns undefined
  }
  </code></pre>
  <pre><code>&lt;ion-input [autofocus]&gt;&lt;/ion-input&gt; &lt;!-- Didn't work --&gt;
  </code></pre>