title: React Native TextInput does not get focus
body: <p>I have this simple code of a <code>TextInput</code> that I want it to get focus when it first renders and on submits. However, it does not get focus at all.</p>
  
  <pre><code>render() {
      return (
        &lt;TextInput
          ref={(c) =&gt; this._input = c}
          style={[styles.item, this.props.style]}
          placeholder={"New Skill"}
          onChangeText={(text) =&gt; {
            this.setState({text})
          }}
          onSubmitEditing={(event) =&gt; {
            this.props.onSubmitEditing(this.state.text);
            this._input.clear();
            this._input.focus();
          }}
        /&gt;
      );
    }
  
    componentDidMount() {
      this._input.focus();
    }
  </code></pre>