title: React Native: Update without forceUpdate?
body: <p>I have a very simple React Native sample here. I am very new to React Native (and also to React).</p>
  
  <p>I have a state with a variable text1. </p>
  
  <p>It is logged to console with button "log data".</p>
  
  <p>It is set to the current timestring with button "change data". </p>
  
  <p>And if an input is done then it will get that data.</p>
  
  <p>The content of text1 is shown in a Text-Element.</p>
  
  <pre><code>import React from 'react';
  import { StyleSheet, Text, View, Button, Alert,TextInput} from 'react-native';
  
  
  export default class App extends React.Component 
  {
      constructor(props) 
      {
          super(props);
          this.state = {text1: 'initial'};
      }
  
      setVal () 
      {
          this.setState (st =&gt; {st.text1 = new Date ().toString ()});
          //this.forceUpdate ();
      }
  
      render()
      {
          return (
              &lt;View style={{ alignItems: 'center', justifyContent: 'center', flex: 1}}&gt;
              &lt;Text style={{fontSize: 30, margin: 40}}&gt;text1 is {this.state.text1}&lt;/Text&gt;
  
  
              &lt;Button
                  onPress={
                              () =&gt; {console.log("text1=" + this.state.text1);
                          }}
                  title="log data"
                  color="green"
              /&gt;
  
              &lt;Button
                  onPress={this.setVal.bind (this)}
                  title="change data"
                  color="orange"
              /&gt;
  
  
             &lt;TextInput
                  style={{height: 40, width: 200, margin: 30, borderColor: 'grey', borderWidth: 2}}
                  onChangeText={str =&gt; this.setState({text1: str})}
                  value={this.state.text1}
              /&gt;
        &lt;/View&gt;
      );
    }
  }
  </code></pre>
  
  <p>If I change text1 by doing an input then the Text-Element is updated immediately. That is not the case if I do it by button "change data" and not call foreceUpdate.</p>
  
  <p>I thought setState would automatically perform update and render.
  ???</p>
  
  <p>Why is that</p>