javascript - TypeError：未定义不是对象（评估“appState.remove”）

Question

我很难解决这个错误，因为现在一切都可以正常工作，它说它已被弃用。有人可以帮我解决错误，因为它没有任何工作，我已经尝试了 App State 文档中的新代码，但仍然是相同的错误TypeError: undefined is not an object (evalating 'appState.remove')

这是我的代码：

constructor(props) {
    super(props);
    this.state = {
      region: null,
      status: undefined,
      appState: AppState?.currentState,
      modalVisible: true,
      isLoading: true,
    };
    this._getLocationAsync();
  }

  componentDidMount() {
    AppState.removeEventListener("change", this.handleAppStateChange);
  }
  handleAppStateChange = (nextAppState) => {
    if (
      this.state.appState.match(/inactive|background/) &&
      nextAppState === "active"
    ) {
      this._getLocationAsync();
    }
    this.setState({ appState: nextAppState });
  };

  componentWillUnmount() {
    AppState.addEventListener("change", this.handleAppStateChange);

    this._getLocationAsync();
  }
  _getLocationAsync = async () => {
    let { status } = await Location.requestPermissionsAsync();
    let location = await Location.getCurrentPositionAsync({
      enableHighAccuracy: false,
      timeout: 10000,
      maximumAge: 0,
    });

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

标签： javascriptreactjsreact-nativelocation

Answer 1

//listen to AppState change in componentDidMount
componentDidMount() {
    this.subscriptionToAppState = AppState.addEventListener("change",  this.handleAppStateChange);
}

//stop listen 
componentWillUnmount() {
    //if your react native version 0.65 or more use this
    this.subscriptionToAppState.remove();
    //if your react native version min than v 0.65 use the deprecated methode like this 
    this.subscriptionToAppState.removeEventListener("change", this.handleAppStateChange);
}