title: Update state when user press back button in React Native
body: <p>I use react-navigation for manage routes. This is my Home component:</p>
  
  <pre><code>class HomeScreen extends React.Component {
     constructor(props) {
        this.state = {
           userProfile: {
              firstname: 'John',
              avatar: 'john-profile.png',
              location: 'Canada',
           }
        }
     }
  
     componentDidMount() {
        AsyncStorage.getItem('userProfile', (errs, result) =&gt; {
           this.setState({userProfile: JSON.parse(result)});
        });
     }
  
     render() {
        return (
           &lt;View&gt;
              &lt;Image src="{this.state.userProfile.avatar}" /&gt;
              &lt;Text&gt;Firstname: {this.state.userProfile.firstname}&lt;/Text&gt;
              &lt;Text&gt;Location: {this.state.userProfile.location}&lt;/Text&gt;
           &lt;/View&gt;
        );
     }
  }
  </code></pre>
  
  <p>And this is the Profile screen:</p>
  
  <pre><code>class ProfileScreen extends React.Component {
     constructor(props) {
        this.state = {
           userProfile: null,
        }
     }
  
     componentDidMount() {
        AsyncStorage.getItem('userProfile', (errs, result) =&gt; {
           this.setState({userProfile: JSON.parse(result)});
        });
     }
  
     save() {
  
        var userSavedProfile = this.state.userProfile;
  
        userSavedProfile.firstname = "Peter";
        userSavedProfile.avatar = "peter-avatar.png";
        userSavedProfile.location = "EEUU";
  
        this.setState({userProfile: userSavedProfile});
  
        AsyncStorage.setItem('userProfile',     JSON.stringify(this.state.userProfile), () =&gt; {});
  
     }
  
     render() {
        return (
           &lt;View&gt;
              &lt;Button title="Save" onPress={() =&gt; this.save()}  /&gt;
           &lt;/View&gt;
        );
     }
  }
  </code></pre>
  
  <p>When I save the new user information and I press back button in header (react-navigation) the user profile is old, firstname = John, etc... How update state from Home when user press back button and refresh data?</p>