title: wants to capture image in by using expo camera
body: <p>i'm trying to capture image from expo camera but when i alert my photo nothing shown up here is complete code of my component </p>
  
  <pre><code>import React from 'react';
   import { Text, View, TouchableOpacity } from 'react-native';
   import { Camera, Permissions } from 'expo';
   import {
  Container,
  
  Title,
  Content,
  Header,
  Button,
  Switch,
  Left,
  Body,
  Right,
  
  List,ListItem,Thumbnail,Footer,FooterTab
   } from "native-base";
    import {Icon} from 'react-native-elements';
  
   export default class CameraEx extends React.Component {
     static navigationOptions = {
      header: null
  }
    state = {
     hasCameraPermission: null,
      type: Camera.Constants.Type.back,
    };
  
    async componentDidMount() {
     const { status } = await Permissions.askAsync(Permissions.CAMERA);
  this.setState({ hasCameraPermission: status === 'granted' });
    }
    takePicture = async function() {
    if (this.camera) {
      let photo = await this.camera.takePictureAsync();
    alert(photo);
  
    }
  
     }
  
      render() {
  const { hasCameraPermission } = this.state;
  if (hasCameraPermission === null) {
    return &lt;View /&gt;;
  } else if (hasCameraPermission === false) {
    return &lt;Text&gt;No access to camera&lt;/Text&gt;;
  } else {
    return (
  
      &lt;Container style={{ flex: 1 }}&gt;
       &lt;Header transparent&gt;
        &lt;Left&gt;
        &lt;Button transparent onPress={() =&gt;this.props.navigation.navigate('Home') }&gt;
         &lt;Icon name='arrow-back' /&gt;
        &lt;/Button&gt;
        &lt;/Left&gt;
  
      &lt;/Header&gt;
        &lt;Camera style={{ flex: 1 }} type={this.state.type}&gt;
          &lt;View
            style={{
              flex: 1,
              backgroundColor: 'transparent',
              flexDirection: 'row',
              justifyContent:'space-between',
              width:"50%"
            }}&gt;
            &lt;TouchableOpacity
              style={{
                //flex: 0.1,
                alignSelf: 'flex-end',
                alignItems: 'center',
              }}
              onPress={() =&gt; {
                this.setState({
                  type: this.state.type === Camera.Constants.Type.back
                    ? Camera.Constants.Type.front
                    : Camera.Constants.Type.back,
                });
              }}&gt;
              &lt;Text
                style={{ fontSize: 18, marginBottom: 10, color: 'white' }}&gt;
                {' '}Flip{' '}
              &lt;/Text&gt;
            &lt;/TouchableOpacity&gt;
            &lt;TouchableOpacity
              style={{
               // flex: 0.1,
                alignSelf: 'flex-end',
                alignItems: 'center',
              }}
              onPress={()=&gt;this.takePicture()}
             &gt;
              &lt;Text
                style={{ fontSize: 18, marginBottom: 10, color: 'white' }}&gt;
                {' '}Take Picture{' '}
              &lt;/Text&gt;
            &lt;/TouchableOpacity&gt;
          &lt;/View&gt;
        &lt;/Camera&gt;
      &lt;/Container&gt;
    );
  }
     }
     }
  </code></pre>
  
  <p>here is a complete code my component please let me know how i can capture image and stored into state i'm beginner .............................................................................................................................................                                                               ....                                                                                             </p>