条件组件渲染反应原生

Question

我正在尝试渲染条件组件。我有带有该位置的 MapView，我想要实现的是：如果该位置是从用户授予的或找不到该位置，而不是 MapView，我想呈现一个 Textinput，用户可以在其中手动键入他们的位置。这是我的代码

export default class GpsLocation extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      region: null,
    };
    this._getLocationAsync();
  }

  _getLocationAsync = async () => {
    let { status } = await Permissions.askAsync(Permissions.LOCATION);
    let location = await Location.getCurrentPositionAsync({
      enableHighAccuracy: true,
    });

    let region = {
      latitude: location.coords.latitude,
      longitude: location.coords.longitude,
      latitudeDelta: 0.0045,
      longitudeDelta: 0.0045,
    };
    this.setState({ region: region });
  };

  render() {
    if (this.status === "granted") {
      return (
        <View style={styles.locationContainer}>
        <Text style={styles.note}>Adresa</Text>
        <MapView
          initialRegion={this.state.region}
          showUserLocation={true}
          showCompass={true}
          rotateEnabled={false}
          style={{ flex: 1, borderRadius: 10 }}
        ></MapView>
      </View>
      );
    } else {
      return (
        <TextInput/>
      );
    }
  }
}

Answer 1

试试这个方法

constructor(props) {
    super(props);
    this.state = {
      region: null,
      status : undefined, // add initially `undefined`
    };
    this._getLocationAsync();
  }

_getLocationAsync = async () => {
    let { status } = await Permissions.askAsync(Permissions.LOCATION);
    .......
    this.setState({ ... , status }); // update status here
  };

render() {
  // change here also
  return this.state.status === "granted" ? (
        <View style={styles.locationContainer}>
          <Text style={styles.note}>Adresa</Text>
          <MapView
            initialRegion={this.state.region}
            showUserLocation={true}
            showCompass={true}
            rotateEnabled={false}
            style={{ flex: 1, borderRadius: 10 }}
          ></MapView>
      </View>
      ) : <TextInput/> ;       
  }