加载字体本机基础错误

Question

I'm getting the error: You started loading 'Roboto_medium', but used it before it finished loading when using native base.

I've followed the instructions in the official page.

To create react native app I'm using create-react-native-app .

App.js

export default class App extends React.Component {

async componentWillMount() {
  await Expo.Font.loadAsync({
  'Roboto': require('native-base/Fonts/Roboto.ttf'),
  'Roboto_medium': require('native-base/Fonts/Roboto_medium.ttf'),
  'Ionicons': require('@expo/vector-icons/fonts/Ionicons.ttf'),
 });
}

 render() {
   return (
    <Container>
      <StatusBar hidden={true} />

    <Button>
      <Text>
        Button
      </Text>
    </Button>

    <ListaItens />
    </Container>
  );
}
} 

Answer 1

you need to wait till the fonts get loaded. You can do something like this

import React from "react";
import { StatusBar } from "react-native";
import { Container, Button, text, ListItem, Text } from "native-base";
import Expo from "expo";

export default class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = { loading: true };
  }

  async componentWillMount() {
    await Expo.Font.loadAsync({
      Roboto: require("native-base/Fonts/Roboto.ttf"),
      Roboto_medium: require("native-base/Fonts/Roboto_medium.ttf"),
      Ionicons: require("@expo/vector-icons/fonts/Ionicons.ttf"),
    });
    this.setState({ loading: false });
  }

  render() {
    if (this.state.loading) {
      return <Expo.AppLoading />;
    }
    return (
      <Container>
        <StatusBar hidden={true} />

        <Button>
          <Text>Button</Text>
        </Button>

        <ListItem />
      </Container>
    );
  }
}

Answer 2

This new code for expo SDK 35 which was modified from @akhil xavier 's answer

First install expo-font

expo install 'expo-font'

here is the App.js

import React from "react";
import * as Font from "expo-font";
import { ActivityIndicator } from "react-native";
import { Root } from "native-base";

export default class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = { loading: true };
  }

  async componentWillMount() {
    await Font.loadAsync({
      Roboto: require("native-base/Fonts/Roboto.ttf"),
      Roboto_medium: require("native-base/Fonts/Roboto_medium.ttf"),
      Ionicons: require("@expo/vector-icons/build/vendor/react-native-vector-icons/Fonts/Ionicons.ttf"),
    });
    this.setState({ loading: false });
  }

  render() {
    if (this.state.loading) {
      return <ActivityIndicator />;
    }
    return (
      <Root>
       <RootPage /> // starter component (i.e. nav)
      </Root>
    );
  }
}

Answer 3

The solution that works for me is below. The error I had was that I imported Font as (Fonts) but while calling it failed to notice the 's'. Fixed it by making sure the import name is similar to what you call the loadAsync to. You need to have 'expo-font' installed in your project for it to work

import React from "react";
import * as Font from "expo-font";
import { AppLoading } from "expo";
import MealsNavigator from "./navigation/MealsNavigator";


const fetchFonts = () => {
  return Font.loadAsync({
    "open-sans": require("./assets/fonts/OpenSans-Regular.ttf"),
    "open-sans-bold": require("./assets/fonts/OpenSans-Bold.ttf")
  });
};

export default function App() {
  const [fontLoaded, setFontLoaded] = useState(false);
  if (!fontLoaded) {
    return (
      <AppLoading
        startAsync={fetchFonts}
        onFinish={() => setFontLoaded(true)}
        onError={err => console.log(err)}
      />
    );
  }
  return <MealsNavigator />;
}

Answer 4

If anyone is having this issue with the 'MaterialIcons' font family, I had a similar problem and found following this solution worked:

https://javascriptrambling.blogspot.com.au/2018/03/expo-icon-fonts-with-react-native-and.html

You basically need to:

1. Install the fonts (using npm install)
2. Do a Font.loadAsync on the fonts in your componentWillMount() function.
3. Remember to mark the componentWillMount() function as async
4. The conditionally display either as 'loading' or with the view depending on the state of a 'loaded' flag.

For example:

import React from 'react';
import { View } from 'react-native';
import { Avatar } from 'react-native-elements';
import { AppLoading, Font } from 'expo';

import FontAwesome  
  from './node_modules/@expo/vector-icons/fonts/FontAwesome.ttf';

import MaterialIcons  
  from './node_modules/@expo/vector-icons/fonts/MaterialIcons.ttf';


export default class App extends React.Component {
  state = {
    fontLoaded: false
  };

  async componentWillMount() {
    try {
      await Font.loadAsync({
        FontAwesome,
        MaterialIcons
      });
      this.setState({ fontLoaded: true });
    } catch (error) {
      console.log('error loading icon fonts', error);
    }
  }

  render() {
    if (!this.state.fontLoaded) {
      return <AppLoading />;
    }

    return (
      <View>
        <Text>My App</Text>
        <Avatar
          small
          rounded
          icon={{ name: 'add' }}
        /> 
      </View>
    );
  }
}

Answer 5

你必须去node_modules / yourPlugin / index.js找到fontFamily并删除它

Answer 6

One reason why it has to load font is because you are using the Native Base Text component. If you import the React Native Text component instead you won't even have to load fonts and you won't see that error.