在React Native中，我拥有的代码没有任何渲染

Question

So I am very confused because in the code below, a button should render, but nothing does. All I get is a blank white screen. I don't get any errors, and the terminal says finished loading javaScript bundle, so the code is working as it should. I don't know why this is happening and I would really like some help.

This is using react native and javascript.

import React, { Component } from 'react';
import { StyleSheet, Text, View, Image, TextInput, ScrollView, TouchableHighlight, Button } from 'react-native';
import { Font } from 'expo';

var fontLoaded = false;

export default class App extends React.Component {

  componentDidMount() {
      Expo.Font.loadAsync({
        'Cabin-Regular-TTF': require('./Cabin-Regular-TTF.ttf'),
      });


  }
  constructor(props) {
    super(props);
    this.state = { postInput: ""}
  }

 render() {
    return (
      <View>
        <View style={styles.container}>
          <View style={{width: 1, height: 30, backgroundColor: '#e8e8e8'}} />
          <Button
            onPress={this.setState({ fontLoaded: true })}
            title="Press Me To Load the App After 15 Seconds!"
            color="#841584"
            accessibilityLabel="Wait 15 seconds and then press me to load the font!"
          />
        </View>


        {fontLoaded ? (
          <View style={styles.container}>
            <Text style={{ fontFamily: 'Cabin-Regular-TTF', fontSize: 16 }}>
                Whats on your mind? Create a post!
            </Text>  

            <TextInput>
                style={{height:40, width: 320, borderColor: '#303030', borderWidth: 1}}
                onChangeText={(postInput)=>this.setState({postInput})}
                value={this.state.postInput}    
            </TextInput>

            <ScrollView>
               <View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
               <View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
               <View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
               <View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
               <View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
               <View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
               <View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
               <View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
               <View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
               <View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
               <View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
               <View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
               <View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
             </ScrollView>
          </View>) : (null) }
      </View>
    );
  }

} // missing one!

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#e8e8e8',
    alignItems: 'center',
    justifyContent: 'center'
  },
});

Answer 1

First I think you have a styling issue. The most outer View should have a flex:1 style prop at least. Also removing justifyContent: 'center' and alignItems: 'center' can help.

Your second problem is caused by onPress prop of the Button . You are executing the function rather than passing it as a parameter.

It should be like below;

onPress={() => this.setState({ fontLoaded: true })}