Comments and otehr restrucuring

Location Tutorial/LocationSearch.swift

@@ -2,8 +2,6 @@
 //  LocationFinder.swift
 //  MapKit Testing Search Functionality
 //
-//  Created by Brian Porumb on 25.11.21.
-//
 
 import Foundation
 import Combine
@@ -11,7 +9,7 @@ import MapKit
 
 class LocationService: NSObject, ObservableObject {
     
-    // Differnt search states
+    // Different search states
     enum LocationStatus: Equatable {
         case idle
         case noResults
@@ -37,11 +35,11 @@ class LocationService: NSObject, ObservableObject {
         self.searchCompleter.delegate = self
         
         // receive a stream from the queryFragment in the view
-        // debounce (wait) for 250miliseconds before pushing the event further
+        // debounce (wait) for 500 milliseconds before pushing the event further
         // sink returns the updated string after waiting the specified amount of time
         queryCancellable = $queryFragment
             .receive(on: DispatchQueue.main)
-            .debounce(for: .milliseconds(250), scheduler: RunLoop.main, options: nil)
+            .debounce(for: .milliseconds(500), scheduler: RunLoop.main, options: nil)
             .sink(receiveValue: { fragment in
                 
                 // if fragment isn't empty then set the queryFrament to the current updated string

Location Tutorial/MapSerachView.swift

 //
-//  ContentView.swift
+//  MapSearchView.swift
 //  MapKit Testing Search Functionality
 //
-//  Created by Brian Porumb on 25.11.21.
-//
 
 import SwiftUI
 

Location Tutorial/ViewController.swift

 //
 //  ViewController.swift
-//  Location Tutorial
-//
-//  Created by Huang on 2021/11/25.
+//  MapKit Routing, Annotations and Location
 //
 
 import UIKit
@@ -14,26 +12,31 @@ class ViewController: UIViewController {
     @IBOutlet weak var mapView: MKMapView!
     let locationManager = CLLocationManager()
     var regionInMeters: Double = 10000 //scale of the map
-    
-    // ### code for directions start ###
-    
     var directionsArray: [MKDirections] = []
     
-    // ### code for directions end ###
-    
     override func viewDidLoad() {
         super.viewDidLoad()
         checkLocationServices()
         setupMapView()
     }
     
+    func setupMapView(){
+        mapView.delegate=self
+    }
     
     func setupLocationManager() {
         locationManager.delegate = self
         locationManager.desiredAccuracy = kCLLocationAccuracyBest
     }
     
-    
+    // helper function to display alerts to user
+    func displayAlert(alertTitle: String, alertMessage: String) {
+        let alert = UIAlertController(title: alertTitle, message: alertMessage, preferredStyle: .alert)
+        alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
+        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
+        self.present(alert, animated: true)
+    }
+        
     func centerViewOnUserLocation() {
         if let location = locationManager.location?.coordinate {
             let region = MKCoordinateRegion.init(center: location, latitudinalMeters: regionInMeters, longitudinalMeters: regionInMeters)
@@ -41,18 +44,18 @@ class ViewController: UIViewController {
         }
     }
     
-    
+    // check if user's location services are enabled
     func checkLocationServices() {
         if CLLocationManager.locationServicesEnabled() {
             setupLocationManager()
             checkLocationAuthorization()
         } else {
-            // Show alert letting the user know they have to turn this on.
+            print("Location Services are not enabled")
+            displayAlert(alertTitle: "Location Services are not turned on", alertMessage: "You must enable your Location Services to perform this action")
         }
     }
     
-    
-    
+    // checking authorization status
     func checkLocationAuthorization() {
         let manager = CLLocationManager()
         switch manager.authorizationStatus {
@@ -76,29 +79,24 @@ class ViewController: UIViewController {
         }
     }
     
-    // ### code for directions start ###
-    
-    func setupMapView(){
-        mapView.delegate=self
-    }
-    
+    // action triggered on the "GO" button tap
     @IBAction func goButtonTapped(_ sender: Any) {
         print("GO button tapped")
         getDirections()
     }
     
-    func getLocationCoordinates() -> CLLocationCoordinate2D {
-        let cologne = MKPointAnnotation()
-        cologne.title = "Cologne"
-        cologne.coordinate = CLLocationCoordinate2D(latitude: 50.9375, longitude: 6.9603)
-        mapView.addAnnotation(cologne)
-        return cologne.coordinate //hard coded coordinates for Cologne
+    //to prevent throttling and multiple renders
+    func resetMapView(withNew directions: MKDirections) {
+        mapView.removeOverlays(mapView.overlays)
+        directionsArray.append(directions)
+        let _ = directionsArray.map { $0.cancel() }
     }
     
-    
+    // main function for routing
     func getDirections() {
         guard let location = locationManager.location?.coordinate else {
-            //TODO: Inform user we don't have their current location
+            print("Location not found")
+            displayAlert(alertTitle: "Location not found", alertMessage: "App cannot access your location")
             return
         }
         
@@ -107,12 +105,21 @@ class ViewController: UIViewController {
         resetMapView(withNew: directions)
         
         directions.calculate { [unowned self] (response, error) in
-            //TODO: Handle error if needed
-            guard let response = response else { return } //TODO: Show response not available in an alert
+            if error != nil {
+                print("Directions couldn't be computed")
+                displayAlert(alertTitle: "Directions couldn't be computed", alertMessage: "App cannot find directions to the destination")
+                return
+            }
+            guard let response = response else {
+                print("Response not found")
+                displayAlert(alertTitle: "Directions couldn't be computed", alertMessage: "App cannot find directions to the destination")
+                return
+            }
             print("total routes found: \(response.routes.count)")
             for route in response.routes {
-                self.mapView.addOverlay(route.polyline, level: .aboveRoads)
-                var directionsRegion: MKCoordinateRegion = MKCoordinateRegion.init(route.polyline.boundingMapRect)
+                self.mapView.addOverlay(route.polyline, level: .aboveRoads) //add an overlay for each route
+                                                                            //polyline: connected line segments that don't form a loop
+                var directionsRegion: MKCoordinateRegion = MKCoordinateRegion.init(route.polyline.boundingMapRect)  // recenter
                 //to increase the span of the region in order to add some margin
                 directionsRegion.span.latitudeDelta *= 1.2
                 directionsRegion.span.longitudeDelta *= 1.2
@@ -121,31 +128,30 @@ class ViewController: UIViewController {
         }
     }
     
+    // creates a new request by configuring different properties
     func createDirectionsRequest(from coordinate: CLLocationCoordinate2D) -> MKDirections.Request {
         let destinationCoordinate       = getLocationCoordinates()
         let startingLocation            = MKPlacemark(coordinate: coordinate) //user's location
         let destination                 = MKPlacemark(coordinate: destinationCoordinate)
-        
         let request                     = MKDirections.Request()
         request.source                  = MKMapItem(placemark: startingLocation)
         request.destination             = MKMapItem(placemark: destination)
         request.transportType           = .automobile
         request.requestsAlternateRoutes = true
-        
         return request
     }
     
-    //to prevent throttling and multiple renders
-    func resetMapView(withNew directions: MKDirections) {
-        mapView.removeOverlays(mapView.overlays)
-        directionsArray.append(directions)
-        let _ = directionsArray.map { $0.cancel() }
+    // hard-coded to return coordinates of Southampton
+    func getLocationCoordinates() -> CLLocationCoordinate2D {
+        let southampton = MKPointAnnotation()
+        southampton.title = "Southampton"
+        southampton.coordinate = CLLocationCoordinate2D(latitude: 50.9097, longitude: -1.4044)
+        mapView.addAnnotation(southampton) // add annotation(a pin) for Southampton
+        return southampton.coordinate
     }
     
-    // ### code for directions end ###
 }
 
-
 extension ViewController: CLLocationManagerDelegate, MKMapViewDelegate {
     
     func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
@@ -158,7 +164,8 @@ extension ViewController: CLLocationManagerDelegate, MKMapViewDelegate {
         checkLocationAuthorization()
     }
     
-    // ### code for directions start ###
+    // called each time the bounding map rectangle of an overlay intersects the visible region of a map
+    // defines 'how' the overlay should look like -> renderer properties are specified here
     func mapView(_ mapView: MKMapView,
                  rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
         let renderer = MKPolylineRenderer(overlay: overlay)
@@ -168,22 +175,22 @@ extension ViewController: CLLocationManagerDelegate, MKMapViewDelegate {
         return renderer
     }
     
+    // Delegate method for annotations
     func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
         guard annotation is MKPointAnnotation else { return nil }
-
         let identifier = "Annotation"
+        // dequeue an existing annotation view before creating a new one as new annotations move on-screen
+        // (performance enhancement)
         var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier)
-
         if annotationView == nil {
             annotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: identifier)
             annotationView!.canShowCallout = true
         } else {
             annotationView!.annotation = annotation
         }
-
         return annotationView
     }
-    // ### code for directions end ###
+    
 }