Use the Map

One of the core features of the HERE SDK for iOS is Mapping, which includes adding a map view, changing the location displayed by the map, and modifying its properties. The primary component of the mapping API is the map view, which is integrated as a UIView subclass. The map view represents a vector based view to display a map and various properties.

HERE map data is updated on a weekly basis to ensure you always get the freshest map data available. By integrating the map view you can automatically benefit from this.

To manipulate the map and its properties it's best to start looking at the Camera section. More features include:

• Map gestures to handle common map gestures and default map behaviors like pan or rotate.
• Map schemes to instantly switch default map styles such as satellite versus normal map layer. More on the available map schemes you can find below.
• Map items to place objects and shapes onto the map and interact with them.
• Custom raster tiles to show custom server images as an additional map layer.
• Custom map styles to load custom map schemes.

Performance Optimization

By default, the MapView is rendered with 60 frames per second (FPS). Via mapView.frameRate the maximum frame rate can be adjusted - for example, to reduce CPU / GPU usage on low end devices. It is also possible to deactivate automatic render cycles by setting FPS to 0. Setting negative values has no effect. The value can be set individually per MapView instance - in case your app contains multiple MapView's.

Another option is to use custom map styles that contain less elements to render.

To shrink the size of the HERE SDK framework, unused fonts can be removed before shipping an application.

More options are explained in the Optimization Guide.

Load Map Schemes

The HERE SDK supports five preconfigured map schemes:

• normalDay: A lossless scaleable vector base map for usage during daylight.
• normalNight: A lossless scaleable vector base map for usage during night.
• hybridDay: A day version of a hybrid scheme combining satellite imagery with vector street network, map labels and POI information.
• hybridNight: A night version of a hybrid scheme combining satellite imagery with vector street network, map labels and POI information.
• satellite: A bitmap based map showing satellite imagery for various zoom stages.

Note that it is also possible to fully customize your own map styles, except for the satellite imagery.

Use the following code snippet to load a map scheme:

MapScheme mapScheme = MapScheme.normalDay;

_hereMapController.mapScene.loadSceneForMapScheme(mapScheme,
    (MapError? error) {
  if (error != null) {
    print('Map scene not loaded. MapError: ${error.toString()}');
    return;
  }

  // ...
});

It is recommended to use the day variants during day time when the surrounding light is brighter. The night variants are optimized for usage when there is less light. For example, an application may switch from day to night scheme when a driver is passing through a tunnel - if you are using the Navigate Edition, you can get notified on changed road attributes to know when you are driving through a tunnel. This allows an application to switch the map scheme on the fly. Note that this is not happening automatically.

The HERE SDK is also not automatically detecting the current time of the day to switch between day and night modes. An application may decide to do this based on the user's configuration or by checking the device clock.

The available map styles are optimized to easily add additional content and overlays onto the base map without visual interference. The map schemes are less colorful and support a clean and neutral tone to maximize readability even in case of color blindness:

• The street network is designed in gray scales and provides a hierarchy through brightness, contrast and widths.
• Colors are overall rather bright set up.
• Key colors are grey, blue, green, white.

In addition, the HERE SDK offers a satellite scheme, that does not contain any labels:

Add Map Layers

On top of map schemes, the HERE SDK allows to add certain kinds of layers that show additional information such as the current traffic flow. Below you can see how such layers can be enabled with one line of code:

_hereMapController.mapScene.setLayerVisibility(MapSceneLayers.trafficFlow, VisibilityState.visible);
_hereMapController.mapScene.setLayerVisibility(MapSceneLayers.trafficIncidents, VisibilityState.visible);
_hereMapController.mapScene.setLayerVisibility(MapSceneLayers.safetyCameras, VisibilityState.visible);
_hereMapController.mapScene.setLayerVisibility(MapSceneLayers.vehicleRestrictions, VisibilityState.visible);
_hereMapController.mapScene.setLayerVisibility(MapSceneLayers.landmarks, VisibilityState.visible);
_hereMapController.mapScene.setLayerVisibility(MapSceneLayers.extrudedBuildings, VisibilityState.visible);
_hereMapController.mapScene.setLayerVisibility(MapSceneLayers.buildingFootprints, VisibilityState.visible);

Note that not all layers are available for all editions. Layers that are not available will not be rendered. Take a look at the layer API Reference to know which layers are supported. Note that adding a layer may have a minimal performance impact on lower-end devices.

Below you can see screenshots for all supported map layers:

Note: The map layers buildingFootprints & extrudedBuildings are enabled by default on the MapView.

Remove Unused Font Files

The HERE SDK contains fonts to render map labels for all supported languages. If you want to optimize the size of the overall app, you can remove selected fonts. For example, the font with Chinese, Japanese and Korean characters includes support for Simplified Chinese (GB2312), Traditional Chinese (Big 5), Japanese (JIS 0208) and Korean (KSC 5601). This font uses the Simplified Chinese ideographs for shared Unicode code points. To remove this font, open the HERE SDK plugin folder and remove the following files:

• For iOS: ios/Frameworks/heresdk.xcframework/ios-arm64/heresdk.framework/geoviz/fonts/DroidSansFallback.ttf.
• For Android:
  1. Unzip android/libs/heresdk-navigate-4.11.4.0.8940.rc1.aar (note that the AAR is a ZIP format).
  2. Inside unzipped AAR folder, remove assets/geoviz/fonts/DroidSansFallback.ttf.
  3. Re-archive the AAR with Android Studio.

When you remove a font, it is recommended to switch the map language to any other language than the removed font. At least one font needs to be left to see any map labels. Note that each time a label needs to be displayed in a language for a font that was removed an error message is logged - for each character that is missing.

Set a Map Language

You can customize the language that is used on the map to show labels for streets, cities and other map data. By default, the local language of a region is used.

Use the HereMapController to set a languageCode as primaryLanguage. This sets the language for the world - or set null to switch back to the default behavior. If a language is not supported in any region of the world, the local language for that region is shown instead.

Geopolitical Views

The HERE SDK supports multiple geographic political views and disputed borders to show the map boundaries based on an international view (default) or a local country view. The local view affects only particular areas on the map when a border and possession or control is claimed by two or more political entities - usually a country.

You can change the default geopolitical view by setting a three letter language code for the politicalView member accessible via SDKOptions. The supported country codes are accessible on the coverage page.

When set, the map view will show all country boundaries according to the geopolitical view of the country that has been set and the MapView will show the borders accordingly.

Note that this is released as a beta feature.

If you want to change the geopolitical view at runtime, use the following code snippet:

// Optionally, clear the cache, so that changing the options has an immediate effect.
SDKCache.fromSdkEngine(SDKNativeEngine.sharedInstance).clearAppCache((error) {
    if (error != null) {
       // ...
    }
});

var options = SDKNativeEngine.sharedInstance.options;
options.politicalView = "ARG";
await SDKNativeEngine.sharedInstance?.dispose();
try {
  SDKNativeEngine.sharedInstance = SDKNativeEngine(options);
} on InstantiationException {
  // Handle exception.
}

Make sure to call this not during any ongoing HERE SDK operation, as setting new options requires also to create a new shared instance. Ideally, set the options and the politicalView only once before initializing the HERE SDK for the first time during the app's lifecycle.

Availability of Map Data

By default, a few regions in the world including Japan, China and Korea, contain limited map data. To get access to the full map data, please get in contact with your HERE representative.

Offline Maps

All map data can be preloaded before usage (also known as active or explicit downloading) or downloaded during online usage (also known as passive or implicit downloading). Both of these strategies require a network connection for data download, but the explicit strategy allows to prepare data in advance and to consume it when a device doesn't have a network connection - while the implicit strategy uses a cache, which can be overwritten during map usage.

Note that certain HERE SDK features may require a specific map version - as indicated in the related API Reference documentation or in this guide.

This is also relevant for cached map data - see the following section. More information on the map version can be found here.

Adapt Map Caching

To better support online and offline use cases, the HERE SDK supports caching of downloaded vector map data. This happens in the background. While interacting with the map, the data is stored locally on the device and can be accessed even when the device loses connection or operates in an offline mode.

The integrated map caching mechanism supports the standard vector based map schemes - satellite images and other raster tiles are also cached, but in a different cache that is not configurable.

Please note that the amount of cached data is limited and will be overwritten with new map data while using the map. In most cases, this is sufficient to give the user the impression of a faster start-up time - as no additional data must be downloaded when you start an app again at the same location as before.

When the cache is full, a least recently used LRU) strategy is applied.

The cache path and maximum size can be specified when manually initializing the HERE SDK using SDKOptions. Note that the cache path can be also set via the Info.plist or AndroidManifest file. Check the Engines section for more details.

This is how you can clear the map cache:

SDKCache.fromSdkEngine(SDKNativeEngine.sharedInstance).clearAppCache((error) {
    if (error != null) {
       // ...
    }
});

Note that disposing the SDKNativeEngine.sharedInstance does not clear the cache.

Questions And Answers Around The Map Cache

• What is a map tile? Map tiles are stored in the map cache. A map tile contains data relevant for search and routing, as well as vector data for the visual representation. It is stored in the Optimized Client Map (OCM) format. Map tiles are available for different zoom levels. A map tile may contain different data, depending on the zoom level.

• What is the impact of missing data in the map cache? Usually, the map cache is never assumed to be complete and there can be always tiles missing for a surrounding area. This is because map tiles get loaded only on demand while they are rendered. When there are tiles missing from the map cache then, for example, the OfflineSearchEngine will not find POIs or road names that are part of the missing tiles and the HERE Rendering Engine cannot render such data. Also, the OfflineRoutingEngine might fail - unless it finds a route around the missing tiles. Note that the OfflineSearchEngine and the OfflineRoutingEngine are not available for every edition.

• What is the size of the map cache? The size of the map cache can be changed by the application. Use at least 256 MB (default). Values above 512 MB or 1 GB are recommended. For turn-by-turn navigation (which is available e.g. for the Navigate Edition), map tiles of zoom level 14 are needed, which equals a circle of roughly 2 km. However, this can vary a bit from location to location.

• What is the eviction policy of the cache? The HERE SDK uses a LRU (least recently used tile) logic to evict the tiles when the map cache becomes full. There is no sophisticated logic to evict, for example, tiles that are farther away from the current location - as it is not foreseeable which areas of the world the user might visit next. However, the map cache is not session-specific, its data from the last time the device was used, ie. from the last power cycle, is still there the next time the app is used. Note that the cache is specific per app, not per device.

• Is any previously cached map tile searchable offline? Yes, it's always searchable with the OfflineSearchEngine. However, sometimes not every map tile contains the same search results for every zoom level. Note that the OfflineSearchEngine is not available for every edition.

• Is only one map tile cached at a time? Yes, only one tile at a time may be added unless its location is on the edge of two tiles. Depending on the zoom level, rendering of the map view will require several tiles - this is not happening automatically and only when the zoom level changes.

• Are satellite images cached? Yes, when the satellite map scheme is set, the corresponding imagery is also cached, but satellite images cannot be used after 90 days (for contractual reasons) and will be evicted. In this case, the HERE SDK checks if there are newer satellite map tiles available and if yes then the images are automatically updated in the cache. If the images have not been changed, then only the timestamp is updated so that the images can be reused after this check for another period of 90 days. However, the LRU strategy still applies. Note that non-satellite map tiles are only evicted when the cache is full - there is no staleness of old tiles and no automatic deletion of old tiles based on time.

• Is there always "base map" available, such as a globe view? The HERE SDK downloads automatically the world tiles, ie. the top most zoom level tiles for the globe. This means that there is always a map available for the globe with a very limited amount of information for rendering purposes. The shapes of countries and continents are visible and capitols are shown with text labels.

• Is the cache auto-cleared? No, a full cache is only cleared based on a LRU strategy (see above). If tiles have not been fully downloaded due to a connectivity interruption, these tiles are preserved and the download continues when connectivity resumes.

• If connectivity is available, will a whole route be cached in advance? No, this is not happening automatically. However, you can use the RoutePrefetcher to download map data into the cache along the route corridor. Look into the turn-by-turn navigation section for more details. Note that the RoutePrefetcher is not available for every edition.

HERE Logo Watermark

When using the HERE SDK, it is required that the HERE logo is always visible on the map view. By default, the HERE logo is located at the bottom right corner of the map. However, you can easily customize its location to meet your app design by calling setWatermarkPosition() on your map view instance. It is recommended to change the default placement, only when it is required due to overlapping UI elements. Note for very small views: If both edges of the map are less than 250 density independent pixels in size, the watermark will be hidden automatically.

Add Support for CarPlay and Android Auto

Currently, the Flutter platform provides no direct support for Apple's CarPlay, Android Auto and Android Automotive.

Therefore, the HERE SDK for Flutter does not support this out-of-the-box.

However, Flutter allows to write custom platform-specific code using method channels.

If you are interested how CarPlay and Android Auto can be implemented with the native HERE SDK variants, take a look below.

• Add support for CarPlay using the HERE SDK for iOS: Follow the Integrate a HERE Map into CarPlay tutorial to see how you can get started and show a map view on a car's head unit display.

• Add support for Android Auto using the HERE SDK for Android: If you want to show a map view on the Desktop Head Unit, you need to render the map using a MapSurface instance. Follow the Integrate a HERE Map into Android Auto tutorial to see how this can be done.

Note that the native SDKs for iOS and Android are already included as part of the Flutter plugin folder that comes bundled with the HERE SDK for Flutter download package.