fix: Load correct nearby location on launch

iosApp/iosApp/Pages/NearbyTransit/NearbyTransitLocationProvider.swift

@@ -9,9 +9,9 @@
 import CoreLocation
 
 class NearbyTransitLocationProvider: ObservableObject {
-    let currentLocation: CLLocationCoordinate2D?
-    let cameraLocation: CLLocationCoordinate2D
-    let isFollowing: Bool
+    var currentLocation: CLLocationCoordinate2D?
+    var cameraLocation: CLLocationCoordinate2D
+    var isFollowing: Bool
 
     @Published var location: CLLocationCoordinate2D
 
@@ -20,6 +20,52 @@ class NearbyTransitLocationProvider: ObservableObject {
         self.cameraLocation = cameraLocation
         self.isFollowing = isFollowing
 
-        location = if isFollowing, currentLocation != nil { currentLocation! } else { cameraLocation }
+        location = Self.resolveLocation(currentLocation, cameraLocation, isFollowing)
+        handleFollowingCamera()
+    }
+
+    static func resolveLocation(
+        _ currentLocation: CLLocationCoordinate2D?,
+        _ cameraLocation: CLLocationCoordinate2D,
+        _ isFollowing: Bool
+    ) -> CLLocationCoordinate2D {
+        if isFollowing, currentLocation != nil { currentLocation! } else { cameraLocation }
+    }
+
+    func updateCurrentLocation(_ newLocation: CLLocationCoordinate2D?) {
+        currentLocation = newLocation
+        handleFollowingCamera()
+        updateLocation()
+    }
+
+    func updateCameraLocation(_ newLocation: CLLocationCoordinate2D) {
+        if cameraLocation.isRoughlyEqualTo(newLocation) {
+            return
+        }
+        cameraLocation = newLocation
+        updateLocation()
+    }
+
+    func updateIsFollowing(_ newFollowing: Bool, withCameraLocation newLocation: CLLocationCoordinate2D? = nil) {
+        isFollowing = newFollowing
+        if newLocation != nil {
+            cameraLocation = newLocation!
+        }
+        handleFollowingCamera()
+        updateLocation()
+    }
+
+    private func updateLocation() {
+        location = Self.resolveLocation(currentLocation, cameraLocation, isFollowing)
+    }
+
+    /*
+      Reset camera location to current location when viewport is following.
+      This prevents loading stale camera locations when the viewport stops following.
+     */
+    private func handleFollowingCamera() {
+        if isFollowing, currentLocation != nil {
+            cameraLocation = currentLocation!
+        }
     }
 }

iosApp/iosApp/Pages/NearbyTransit/NearbyTransitPageView.swift

@@ -14,7 +14,7 @@ import SwiftUI
 @_spi(Experimental) import MapboxMaps
 
 struct NearbyTransitPageView: View {
-    let currentLocation: CLLocationCoordinate2D?
+    var currentLocation: CLLocationCoordinate2D?
     @ObservedObject var globalFetcher: GlobalFetcher
     @ObservedObject var nearbyFetcher: NearbyFetcher
     @ObservedObject var scheduleFetcher: ScheduleFetcher
@@ -23,7 +23,9 @@ struct NearbyTransitPageView: View {
     @ObservedObject var alertsFetcher: AlertsFetcher
 
     @State var cancellables: [AnyCancellable]
-    @State var locationProvider: NearbyTransitLocationProvider
+    @StateObject var locationProvider: NearbyTransitLocationProvider
+
+    let inspection = Inspection<Self>()
 
     init(
         currentLocation: CLLocationCoordinate2D?,
@@ -43,16 +45,16 @@ struct NearbyTransitPageView: View {
         self.alertsFetcher = alertsFetcher
 
         cancellables = .init()
-        locationProvider = .init(
+        _locationProvider = StateObject(wrappedValue: .init(
             currentLocation: currentLocation,
             cameraLocation: viewportProvider.cameraState.center,
             isFollowing: viewportProvider.viewport.isFollowing
-        )
+        ))
     }
 
     var body: some View {
         NearbyTransitView(
-            locationProvider: locationProvider,
+            location: locationProvider.location,
             globalFetcher: globalFetcher,
             nearbyFetcher: nearbyFetcher,
             scheduleFetcher: scheduleFetcher,
@@ -64,36 +66,20 @@ struct NearbyTransitPageView: View {
                 viewportProvider.$cameraState
                     .debounce(for: .seconds(0.5), scheduler: DispatchQueue.main)
                     .sink { newCameraState in
-                        let shouldUpdateLocation = !viewportProvider.viewport.isFollowing &&
-                            !locationProvider.location.isRoughlyEqualTo(newCameraState.center)
-                        if shouldUpdateLocation {
-                            locationProvider = .init(
-                                currentLocation: currentLocation,
-                                cameraLocation: newCameraState.center,
-                                isFollowing: viewportProvider.viewport.isFollowing
-                            )
-                        }
+                        locationProvider.updateCameraLocation(newCameraState.center)
                     }
             )
         }
         .onChange(of: currentLocation) { newLocation in
-            let shouldUpdateLocation = viewportProvider.viewport.isFollowing
-                && !locationProvider.location.isRoughlyEqualTo(newLocation)
-            if shouldUpdateLocation {
-                locationProvider = .init(
-                    currentLocation: newLocation,
-                    cameraLocation: viewportProvider.cameraState.center,
-                    isFollowing: viewportProvider.viewport.isFollowing
-                )
-            }
+            locationProvider.updateCurrentLocation(newLocation)
         }
         .onChange(of: viewportProvider.viewport) { newViewport in
-            locationProvider = .init(
-                currentLocation: currentLocation,
-                cameraLocation: viewportProvider.cameraState.center,
-                isFollowing: newViewport.isFollowing
+            locationProvider.updateIsFollowing(
+                newViewport.isFollowing,
+                withCameraLocation: viewportProvider.cameraState.center
             )
         }
+        .onReceive(inspection.notice) { inspection.visit(self, $0) }
         .navigationTitle("Nearby Transit")
         .navigationBarTitleDisplayMode(.inline)
     }

iosApp/iosApp/Pages/NearbyTransit/NearbyTransitView.swift

@@ -15,7 +15,7 @@ import SwiftUI
 
 struct NearbyTransitView: View {
     @Environment(\.scenePhase) private var scenePhase
-    @ObservedObject var locationProvider: NearbyTransitLocationProvider
+    var location: CLLocationCoordinate2D
     @ObservedObject var globalFetcher: GlobalFetcher
     @ObservedObject var nearbyFetcher: NearbyFetcher
     @ObservedObject var scheduleFetcher: ScheduleFetcher
@@ -44,14 +44,14 @@ struct NearbyTransitView: View {
             }
         }
         .onAppear {
-            getNearby(location: locationProvider.location)
+            getNearby(location: location)
             joinPredictions()
             didAppear?(self)
         }
         .onChange(of: globalFetcher.response) { _ in
-            getNearby(location: locationProvider.location)
+            getNearby(location: location)
         }
-        .onChange(of: locationProvider.location) { newLocation in
+        .onChange(of: location) { newLocation in
             getNearby(location: newLocation)
         }
         .onChange(of: nearbyFetcher.nearbyByRouteAndStop) { _ in
@@ -76,7 +76,7 @@ struct NearbyTransitView: View {
         }
         .replaceWhen(nearbyFetcher.errorText) { errorText in
             IconCard(iconName: "network.slash", details: errorText)
-                .refreshable(nearbyFetcher.loading) { getNearby(location: locationProvider.location) }
+                .refreshable(nearbyFetcher.loading) { getNearby(location: location) }
         }
     }