Appstate 继续在 Android 中更改 React Native

Question

I am working on React native project and there I am taking location permissions. Also I have to track location permissions always like if user has given permission access after install the application and then after sometime user goes to the app settings in device settings and disable/revoked the permissions. Again once app comes from background to foreground, I have to check permission based on that, Needs to show the messages.

So that, I am using Appstate. But, In Android strangely, After installed the application, If user denied the permission with "Dont show again" checkbox, Then Appstate getting keep on changing with background and active always. It is keep on loop.

componentDidMount = async () => {
    AppState.addEventListener('change', this.handleAppStateChange);
  };

  componentWillUnmount() {
    AppState.removeEventListener('change', this.handleAppStateChange);
    Geolocation.clearWatch(this.watchID);
  }

  handleAppStateChange = async nextAppState => {
    const {appState} = this.state;
    console.log('nextAppState -->', nextAppState);
    console.log('appState -->', appState);
    if (appState === 'active') {
      // do this
      this.showLoader();
      await this.requestAndroidLocationPermission();
    } else if (appState === 'background') {
      // do that
    } else if (appState === 'inactive') {
      // do that other thing
    }

    this.setState({appState: nextAppState});
  };

requestAndroidLocationPermission = async () => {
    try {
      const granted = await PermissionsAndroid.request(
        PermissionsAndroid.PERMISSIONS.ACCESS_FINE_LOCATION,
        {},
      );
      if (granted === PermissionsAndroid.RESULTS.GRANTED) {
        this.getLatitudeLongitude();
      } else if (granted === PermissionsAndroid.RESULTS.NEVER_ASK_AGAIN) {
        this.hideLoader();
        this.setState({
          errorMessage: 'Location permission is denied',
          isLoading: false,
        });
      } else {
        this.hideLoader();
        this.requestAndroidLocationPermission();
      }
    } catch (err) {
      console.warn(err);
    }
  };

It is keep on printing (loop) after denied permission with Don't show again

appState --> active
nextAppState --> background
appState --> active
nextAppState --> background
appState --> active
nextAppState --> background
appState --> active

It goes on and never stop.

How to handle this? Any suggestions?

Answer 1

I had the same problem. Do not use AppState. Is faulty.

the problem lies within RN's definition of "background". react-native uses android's activity (the holder of the UI thread and where your UI lives) onPause callback as the trigger for sending the "background" signal. But, onPause is called everytime SOMETHING comes in front of your activity's view hierachy, like Dialogs (like the permission box), other activities (like a file picker), etc; for android react-native, "background" means "shadowed by a foreign UI element/android task" rather than "paused and sent to background to do something else", thus causing the loops you see. The shortest solution is to override onPause in your ReactActivity, and add control conditions to make sure super.onPause is only called when you are actually going to background, like checking your task stack, or if the permission dialog is being called, so you avoid this kind of loop/faulty call. A second option would be to provide your own app lifecycle event instead, with clear triggering conditions.

Answer 2

today I had a similar problem.

I could solve it using "focus" in android and "change" in ios.

I have a custom hook like this:

import { useEffect } from 'react';
import { AppState, Platform } from 'react-native';


const focusEvent = Platform.OS === 'ios' ? 'focus' : 'change';

const useLocationListener = () => {


  useEffect(() => {
    AppState.addEventListener(focusEvent, handleAppStateChange);

    getLocationAsync();
    return () => {
      AppState.removeEventListener(focusEvent, handleAppStateChange);
    };
  }, []);

  const handleAppStateChange = (nextAppState: string) => {
    if (nextAppState === 'active') {
      getLocationAsync();
    }
  };

  const getLocationAsync = async () => {
    const { canAskAgain, status } = await Permissions.getAsync(
      Permissions.LOCATION
    );

    if (canAskAgain) {
      const response = await Permissions.askAsync(Permissions.LOCATION);
       // handle location 
    } 
       // handle location with "status"
    
  };
};

export default useLocationListener;

Answer 3

You can use a flag that check whether app should handle background or it's just a permission call.

const shouldHandleBackground = useRef(true)

const handler = (state) => { 
    if (state === 'active' && shouldHandleBackground.current) { 
        doStuff() 
    }
}

// when calling for permisson make the flag false

shouldHandleBackground.current = false
await Android.permission.LocationPermission()
shouldHandleBackground.current = true

and after permission request you can make flag true