title: react-native page not rendering, but no errors
body: <p>This is the page code:</p>
  
  <pre><code>import React from 'react';
  import { StyleSheet, Text, View, Picker, TouchableHighlight } from 'react-native'; 
  
  export default class SelectHours extends React.Component {
    render() {
      let tpd = this.props.navigation.getParam('tpd', 'two');
  
      switch(tpd) {
      case '1':
        tpd = 'one';
        break;
      case '2':
        tpd = 'two';
        break;
      case '3':
        tpd = 'three';
        break;
      case '4':
        tpd = 'four';
        break;
      default:
        alert(tpd);
      }
  
      return (
        &lt;View styles={styles.container}&gt;
          {tpd != 'one' ? true : false &amp;&amp;
            &lt;View styles={styles.choices}&gt;  
              &lt;Text&gt;Please select a time for each period of the day:&lt;/Text&gt;
              &lt;View styles={styles.choice}&gt;
                &lt;Text&gt;Morning:&lt;/Text&gt;
                &lt;Picker
                  selectedValue={this.state.morning}
                  style={{ height: 50, width: 50 }}
                  onValueChange={(itemValue, itemIndex) =&gt; this.setState({morning: itemValue})}&gt;
                  &lt;Picker.Item label='1' value={1}/&gt;
                  &lt;Picker.Item label='2' value={2}/&gt;
                  &lt;Picker.Item label='3' value={3}/&gt;
                  &lt;Picker.Item label='4' value={4}/&gt;
                  &lt;Picker.Item label='5' value={5}/&gt;
                  &lt;Picker.Item label='6' value={6}/&gt;
                  &lt;Picker.Item label='7' value={7}/&gt;
                  &lt;Picker.Item label='8' value={8}/&gt;
                  &lt;Picker.Item label='9' value={9}/&gt;
                  {tpd === 'two' ? true : false &amp;&amp;
                    &lt;View&gt;
                      &lt;Picker.Item label='10' value={10}/&gt;
                      &lt;Picker.Item label='11' value={11}/&gt;
                    &lt;/View&gt;
                  }
                &lt;/Picker&gt;
                &lt;Text&gt;AM&lt;/Text&gt;
              &lt;/View&gt;
              &lt;View&gt;
                {tpd === 'four' ? true : false &amp;&amp;
                  &lt;View styles={styles.choice}&gt;
                    &lt;Text&gt;Late morning:&lt;/Text&gt;
                    &lt;Picker
                      selectedValue={this.state.late_morning}
                      style={{ height: 50, width: 50 }}
                      onValueChange={(itemValue, itemIndex) =&gt; this.setState({late_morning: itemValue})}&gt;
                      &lt;Picker.Item label='10' value={10}/&gt;
                      &lt;Picker.Item label='11' value={11}/&gt;
                    &lt;/Picker&gt;
                    &lt;Text&gt;AM&lt;/Text&gt;
                  &lt;/View&gt;
                }
              &lt;/View&gt;
              &lt;View&gt;
                {tpd != 'two' ? true : false &amp;&amp;
                  &lt;View styles={styles.choice}&gt;
                    &lt;Text&gt;Afternoon&lt;/Text&gt;
                    &lt;Picker
                      selectedValue={this.state.afternoon}
                      style={{ height: 50, width: 50 }}
                      onValueChange={(itemValue, itemIndex) =&gt; this.setState({afternoon: itemValue})}&gt;
                      &lt;Picker.Item label='12' value={12}/&gt;
                      &lt;Picker.Item label='1' value={13}/&gt;
                      &lt;Picker.Item label='2' value={14}/&gt;
                      &lt;Picker.Item label='3' value={15}/&gt;
                      &lt;Picker.Item label='4' value={16}/&gt;
                      &lt;Picker.Item label='5' value={17}/&gt;
                    &lt;/Picker&gt;
                    &lt;Text&gt;PM&lt;/Text&gt;
                  &lt;/View&gt;
                }
                &lt;View styles={styles.choice}&gt;
                  &lt;Text&gt;Nighttime&lt;/Text&gt;
                  &lt;Picker
                    selectedValue={this.state.nighttime}
                    style={{ height: 50, width: 50 }}
                    onValueChange={(itemValue, itemIndex) =&gt; this.setState({nighttime: itemValue})}&gt;
                    {tpd === 'two' ? true : false &amp;&amp;
                      &lt;View&gt;
                        &lt;Picker.Item label='12' value={12}/&gt;
                        &lt;Picker.Item label='1' value={13}/&gt;
                        &lt;Picker.Item label='2' value={14}/&gt;
                        &lt;Picker.Item label='3' value={15}/&gt;
                        &lt;Picker.Item label='4' value={16}/&gt;
                        &lt;Picker.Item label='5' value={17}/&gt;
                      &lt;/View&gt;
                    }
                    &lt;Picker.Item label='6' value={18}/&gt;
                    &lt;Picker.Item label='7' value={19}/&gt;
                    &lt;Picker.Item label='8' value={20}/&gt;
                    &lt;Picker.Item label='9' value={21}/&gt;
                    &lt;Picker.Item label='10' value={22}/&gt;
                    &lt;Picker.Item label='11' value={23}/&gt;
                    &lt;Picker.Item label='12' value={24}/&gt;
                  &lt;/Picker&gt;
                  &lt;Text&gt;PM&lt;/Text&gt;
                &lt;/View&gt;
              &lt;/View&gt;
            &lt;/View&gt;
          }
          &lt;View style={styles.choices}&gt;
            {tpd == 'one' || tpd == 'one/shortcut' ? true : false &amp;&amp;
              &lt;View&gt;
                {tpd == 'one/shortcut' ? true : false &amp;&amp;
                  &lt;Text&gt;What time would you like to start taking your medication every day?&lt;/Text&gt; 
                } 
                &lt;Picker
                  selectedValue={this.state.once}
                  style={{ height: 50, width: 50 }}
                  onValueChange={(itemValue, itemIndex) =&gt; this.setState({once: itemValue})}&gt;
                  &lt;Picker.Item label='1 AM' value={1}/&gt;
                  &lt;Picker.Item label='2 AM' value={2}/&gt;
                  &lt;Picker.Item label='3 AM' value={3}/&gt;
                  &lt;Picker.Item label='4 AM' value={4}/&gt;
                  &lt;Picker.Item label='5 AM' value={5}/&gt;
                  &lt;Picker.Item label='6 AM' value={6}/&gt;
                  &lt;Picker.Item label='7 AM' value={7}/&gt;
                  &lt;Picker.Item label='8 AM' value={8}/&gt;
                  &lt;Picker.Item label='9 AM' value={9}/&gt;
                  &lt;Picker.Item label='10 AM' value={10}/&gt;
                  &lt;Picker.Item label='11 AM' value={11}/&gt;
                  &lt;Picker.Item label='12 PM' value={12}/&gt;
                  &lt;Picker.Item label='1 PM' value={13}/&gt;
                  &lt;Picker.Item label='2 PM' value={14}/&gt;
                  &lt;Picker.Item label='3 PM' value={15}/&gt;
                  &lt;Picker.Item label='4 PM' value={16}/&gt;
                  &lt;Picker.Item label='5 PM' value={17}/&gt;
                  &lt;Picker.Item label='6 PM' value={18}/&gt;
                  &lt;Picker.Item label='7 PM' value={19}/&gt;
                  &lt;Picker.Item label='8 PM' value={20}/&gt;
                  &lt;Picker.Item label='9 PM' value={21}/&gt;
                  &lt;Picker.Item label='10 PM' value={22}/&gt;
                  &lt;Picker.Item label='11 PM' value={23}/&gt;
                  &lt;Picker.Item label='12 PM' value={24}/&gt;
                &lt;/Picker&gt;
              &lt;/View&gt;
            }
          &lt;/View&gt;
        &lt;/View&gt;
      );
    }
  
    constructor() {
      super();
      this.state = {
        morning: 5,
        late_morning: 10,
        afternoon: 14,
        nighttime: 8,
        once: 12
      }
    }
  
    methodSelect = () =&gt; {
  
    }
  }
  
  const styles = StyleSheet.create({
    container: {
      flex: 1,
      backgroundColor: '#fff',
      alignItems: 'center',
      justifyContent: 'center',
    },
    choices: {
      flex: 1,
      backgroundColor: '#fff',
      alignItems: 'center',
      justifyContent: 'space-between',
    },
    choice: {
      flex: 1,
      flexDirection: 'row',
      backgroundColor: '#fff',
      alignItems: 'center',
      justifyContent: 'space-between',
    },
  });
  </code></pre>
  
  <p>Why is it not rendering any of the elements? The page comes up blank, just showing the <code>header</code> and <code>back</code> button. I have <code>alert</code>ed the variable (as you can see above), and it is showing the correct values, and should agree with at least one of the conditional statements.</p>