fix: location flow on iOS devices

src/app/modules/data/list/food-data-list.component.ts

@@ -13,7 +13,9 @@
  * this program. If not, see <https://www.gnu.org/licenses/>.
  */
 import {Component} from '@angular/core';
+import {MapPosition} from '../../map/position.service';
 import {SearchPageComponent} from './search-page.component';
+import {Geolocation} from '@capacitor/geolocation';
 
 /**
  * Presents a list of places for eating/drinking
@@ -91,4 +93,28 @@ export class FoodDataListComponent extends SearchPageComponent {
       ];
     }
   }
+
+  async ionViewWillEnter() {
+    await super.ionViewWillEnter();
+    this.subscriptions.push(
+      this.positionService
+        .watchCurrentLocation(this.constructor.name, {enableHighAccuracy: false, maximumAge: 1000})
+        .subscribe({
+          next: (position: MapPosition) => {
+            this.positionService.position = position;
+          },
+          error: async _error => {
+            this.positionService.position = undefined;
+            await Geolocation.checkPermissions();
+          },
+        }),
+    );
+  }
+
+  ionViewWillLeave() {
+    void this.positionService.clearWatcher(this.constructor.name);
+    for (const sub of this.subscriptions) {
+      sub.unsubscribe();
+    }
+  }
 }

src/app/modules/map/page/map-page.component.ts

@@ -260,6 +260,11 @@ export class MapPageComponent {
    * Subscribe to needed observables and get the location status when user is entering the page
    */
   async ionViewWillEnter() {
+    if (this.positionService.position) {
+      this.position = this.positionService.position;
+      this.positionMarker = MapProvider.getPositionMarker(this.position, 'stapps-device-location', 32);
+    }
+
     this.subscriptions.push(
       this.dataRoutingService.itemSelectListener().subscribe(async item => {
         // in case the list item is clicked
@@ -269,17 +274,19 @@ export class MapPageComponent {
           void this.router.navigate(['/data-detail', item.uid]);
         }
       }),
-      this.positionService.watchCurrentLocation({maximumAge: 3000}).subscribe({
-        next: (position: MapPosition) => {
-          this.position = position;
-          this.positionMarker = MapProvider.getPositionMarker(position, 'stapps-device-location', 32);
-        },
-        error: async _error => {
-          this.locationStatus = await Geolocation.checkPermissions();
-          // eslint-disable-next-line unicorn/no-null
-          this.position = null;
-        },
-      }),
+      this.positionService
+        .watchCurrentLocation(this.constructor.name, {enableHighAccuracy: true, maximumAge: 1000})
+        .subscribe({
+          next: (position: MapPosition) => {
+            this.position = position;
+            this.positionMarker = MapProvider.getPositionMarker(position, 'stapps-device-location', 32);
+          },
+          error: async _error => {
+            this.locationStatus = await Geolocation.checkPermissions();
+            // eslint-disable-next-line unicorn/no-null
+            this.position = null;
+          },
+        }),
     );
 
     // get detailed location status (diagnostics only supports devices)
@@ -290,6 +297,7 @@ export class MapPageComponent {
    * Unsubscribe from all subscriptions when user leaves page
    */
   ionViewWillLeave() {
+    void this.positionService.clearWatcher(this.constructor.name);
     for (const sub of this.subscriptions) {
       sub.unsubscribe();
     }

src/app/modules/map/page/map-page.html

@@ -96,12 +96,12 @@
       <ion-icon *ngIf="position !== null; else noLocationIcon" name="my_location"></ion-icon>
       <ng-template #noLocationIcon>
         <ion-icon
-          *ngIf="locationStatus.location !== 'denied'; else deniedLocationIcon"
-          name="location_searching"
+          *ngIf="locationStatus && locationStatus.location === 'denied'; else pendingLocationIcon"
+          name="location_disabled"
         ></ion-icon>
       </ng-template>
-      <ng-template #deniedLocationIcon>
-        <ion-icon name="location_disabled"></ion-icon>
+      <ng-template #pendingLocationIcon>
+        <ion-icon name="location_searching"></ion-icon>
       </ng-template>
     </ion-button>
   </div>

src/app/modules/map/position.service.spec.ts

@@ -58,9 +58,30 @@ describe('PositionService', () => {
   });
 
   it('should continuously provide (watch) location of the device', done => {
-    positionService.watchCurrentLocation().subscribe(location => {
+    positionService.watchCurrentLocation('testCaller').subscribe(location => {
       expect(location).toBeDefined();
       done();
     });
   });
+
+  it('should stop to continuously provide (watch) location of the device', done => {
+    positionService.watchers.set(
+      'clearWatch',
+      new Promise(resolve => {
+        setTimeout(function () {
+          resolve(`watcherID123`);
+        }, 20);
+      }),
+    );
+    positionService
+      .clearWatcher('clearWatch')
+      .then(result => {
+        expect(result).toBeUndefined();
+        done();
+      })
+      .catch(error => {
+        expect(error).toBeUndefined();
+        done();
+      });
+  });
 });

src/app/modules/map/position.service.ts

@@ -45,6 +45,11 @@ export class PositionService {
    */
   position?: MapPosition;
 
+  /**
+   * Map of callers and their running watchers. Both by their ID
+   */
+  watchers: Map<string, Promise<string>> = new Map();
+
   /**
    * Gets current coordinates information of the device
    *
@@ -84,19 +89,19 @@ export class PositionService {
   /**
    * Watches (continuously gets) current coordinates information of the device
    *
+   * @param caller Identifier for later reference. (I.e use of `clearWatcher`)
    * @param options Options which define which data should be provided (e.g. how accurate or how old)
    */
-  watchCurrentLocation(options: PositionOptions = {}): Observable<MapPosition> {
+  watchCurrentLocation(caller: string, options: PositionOptions = {}): Observable<MapPosition> {
     return new Observable(subscriber => {
-      void Geolocation.watchPosition(options, (position, error) => {
+      const watcherID = Geolocation.watchPosition(options, (position, error) => {
         if (error) {
           subscriber.error(position);
         } else {
           this.position = {
-            heading:
-              Number.isNaN(position?.coords.heading) || position?.coords.heading == undefined
-                ? undefined
-                : position.coords.heading,
+            // TODO use native compass heading instead
+            // waiting for https://github.com/ionic-team/capacitor-plugins/issues/1192
+            heading: undefined,
             latitude: position?.coords.latitude ?? 0,
             longitude: position?.coords.longitude ?? 0, // TODO: handle null position
           };
@@ -104,6 +109,19 @@ export class PositionService {
           subscriber.next(this.position);
         }
       });
+      this.watchers.set(caller, watcherID);
     });
   }
+
+  /**
+   * Clears watcher for a certain caller
+   *
+   * @param caller Identifier of the caller wanting to clear the watcher
+   */
+  async clearWatcher(caller: string): Promise<void> {
+    const watcherID = await this.watchers.get(caller);
+    if (watcherID) {
+      Geolocation.clearWatch({id: watcherID});
+    }
+  }
 }