Flutter中HERE SDK获取当前位置错误及路线计算启动后崩溃问题的解决与try-catch处理咨询

Hey there! Let's break down your two HERE SDK 4.8.0.0 issues in Flutter and walk through actionable solutions, plus how to handle these scenarios with try-catch blocks.

1. Fixing Current Location Retrieval Errors #

First up, let's tackle the location fetch failures. Here are the most common fixes to check:

• Verify Permissions Properly
  Both Android and iOS require explicit location permissions to access device location. Make sure you've added the right entries to your platform config files, then use a package like permission_handler to request authorization before calling any location APIs:

  final status = await Permission.locationWhenInUse.request();
  if (!status.isGranted) {
    // Show a dialog prompting the user to enable permissions in settings
    return;
  }
  

  For Android, add these to AndroidManifest.xml:

  <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
  <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
  

  For iOS, add this to Info.plist:

  <key>NSLocationWhenInUseUsageDescription</key>
  <string>Need location access for navigation features</string>
  

• Ensure Correct SDK Initialization
  Your HERE SDK must be initialized with a valid API key before any location or routing operations. Wrap initialization in a try-catch to catch setup errors early:

  await WidgetsFlutterBinding.ensureInitialized();
  try {
    await SDKNativeEngine.makeSharedInstance("YOUR_VALID_HERE_API_KEY");
  } on InstantiationException catch (e) {
    print("SDK Initialization Failed: ${e.errorCode}");
    // Handle failure (e.g., show an error message to the user)
  }
  

• Check Device Location Services
  Even with permissions, if the user's device has location services turned off, location calls will fail. Add a check to prompt the user to enable services:

  final isLocationEnabled = await Geolocator.isLocationServiceEnabled();
  if (!isLocationEnabled) {
    // Redirect user to device location settings
  }
  

• Validate Location Engine Setup
  Make sure you're using the HERE LocationEngine correctly, and start it only after confirming permissions are granted:

  final locationEngine = LocationEngine();
  locationEngine.addLocationListener((location) {
    // Process the retrieved location data
  });
  try {
    await locationEngine.start();
  } on LocationException catch (e) {
    print("Failed to start Location Engine: ${e.errorCode}");
  }
  

2. Fixing "Are you off-road?" Log & Navigation Crashes #

That log message signals the SDK can't match your current position to a mapped road, which can lead to unhandled crashes if left unattended. Here's how to resolve this:

• Use Accurate Start Coordinates
  If starting navigation from the user's current location, ensure that location is precise (use getCurrentLocation() with high accuracy) instead of hardcoding or using a rough estimate. A start point too far off-road will prevent the SDK from aligning with a valid route.

• Tweak Route Calculation Options
  Explicitly configure your route options to prioritize road-based paths, which helps the SDK generate valid routes:

  final routeOptions = CarOptions();
  routeOptions.avoidFeatures = [AvoidFeature.offRoad];
  routeOptions.routeOptions = RouteOptions(routeType: RouteType.fastest);
  

  Always handle empty results or errors immediately when calculating routes:

  routingEngine.calculateRoute(waypoints, routeOptions, (error, routes) {
    if (error != null) {
      print("Route Calculation Error: ${error.errorCode}");
      return;
    }
    if (routes?.isEmpty ?? true) {
      print("No valid routes found");
      return;
    }
    // Proceed with navigation only if valid routes exist
    startNavigation(routes!.first);
  });
  

• Add Navigation Error Handling
  Attach a NavigationListener to catch issues like route loss or off-road status before they cause crashes:

  final navigationEngine = NavigationEngine();
  navigationEngine.addNavigationListener(NavigationListener(
    onPositionUpdated: (position) {
      if (!position.isOnRoute) {
        // Show a warning to the user and offer to re-calculate the route
        reCalculateRoute();
      }
    },
    onNavigationError: (error) {
      print("Navigation Error Detected: ${error.errorCode}");
      navigationEngine.stopNavigation();
      // Clean up resources or re-initialize navigation flow
    },
    onDestinationReached: () {
      navigationEngine.stopNavigation();
    }
  ));
  

• Enable Debug Logs
  To get more context on the crash, enable debug-level logging for the HERE SDK:

  SDKNativeEngine.setLogLevel(LogLevel.debug);
  

  This will print detailed internal logs that can pinpoint exactly why the crash is occurring.

Handling Exceptions with Try-Catch #

HERE SDK methods throw specific exceptions like InstantiationException, LocationException, and RoutingException—you can catch these explicitly, plus general exceptions, to prevent app crashes and handle errors gracefully:

Example 1: Safe SDK Initialization #

Future<void> initHERE() async {
  try {
    await SDKNativeEngine.makeSharedInstance("YOUR_API_KEY");
  } on InstantiationException catch (e) {
    print("SDK Init Failed: ${e.message}");
    // Show a user-friendly error dialog
  } catch (e) {
    print("Unexpected Initialization Error: $e");
  }
}

Example 2: Safe Location Fetch #

Future<Location?> fetchCurrentLocation() async {
  final status = await Permission.location.request();
  if (!status.isGranted) return null;

  try {
    final locationEngine = LocationEngine();
    return await locationEngine.getCurrentLocation();
  } on LocationException catch (e) {
    print("Location Fetch Error: ${e.errorCode}");
    return null;
  } catch (e) {
    print("Unexpected Location Error: $e");
    return null;
  }
}

Example 3: Safe Navigation Startup #

void startNavigation(Route route) {
  try {
    final navigationEngine = NavigationEngine();
    navigationEngine.startNavigation(route);
    // Attach navigation listeners here as shown earlier
  } catch (e) {
    print("Navigation Start Error: $e");
    // Handle failure (e.g., show an error message to the user)
  }
}

Note: For callback-based operations (like route calculation), wrap the callback logic in try-catch blocks too—outer try-catches won't catch errors inside callbacks.

内容的提问来源于stack exchange，提问作者Muhammed Emin Aydın