I created a class to get the current heading with CLLocationManagerDelegate for my SwiftUI app, but I have the Property 'self.heading' not initialized at super.init call error. I don't know why. I do not think I need to specify a parameter because my class does not take any parameters during its call ?
My LocationManager class:
class LocationManager: NSObject, CLLocationManagerDelegate, ObservableObject {
var locationManager: CLLocationManager?
var objectWillChange = PassthroughSubject<Void, Never>()
#Published var heading: Double {
willSet {
objectWillChange.send()
}
}
override init() {
super.init()
locationManager = CLLocationManager()
locationManager!.delegate = self
locationManager!.desiredAccuracy = kCLLocationAccuracyBest
locationManager!.requestWhenInUseAuthorization()
}
func locationManager(_ manager: CLLocationManager, didUpdateHeading newHeading: CLHeading) {
self.heading = newHeading.trueHeading.degreesToRadians
}
}
You MUST initial all instance variables of the current class before initializing the super.
So add some initial value to heading before calling super.init() like:
override init() {
heading = 0 // Or anything you need
super.init()
locationManager = CLLocationManager()
locationManager!.delegate = self
locationManager!.desiredAccuracy = kCLLocationAccuracyBest
locationManager!.requestWhenInUseAuthorization()
}
Related
In the following code, I have a LocationManager class which provides the city name of the current location via the #Published property wrapper lastSearchedCity.
Then I have a SearchManagerViewModel class that should be in charge of presenting the city name on SwiftUI views based on some conditions (not currently shown in the code below) via the #Published property wrapper cityName. It properly shows the city name when I call the searchAndSetCity() method from ContentView.swift inside an onAppear modifier.
My issue is that if the user turned Location Services off and turns it back On while he/she is in the ContentView.swift the Text view doesn't update, which is understandable since the searchAndSetCity() method would need to be called again.
How can I call the searchAndSetCity() method located inside the SearchManagerViewModel class every time the locationManagerDidChangeAuthorization(_ manager: CLLocationManager) method is called? I believed this method is called every time the authorization status changes.
LocationManager Class
final class LocationManager: NSObject, ObservableObject, CLLocationManagerDelegate {
private let locationManager = CLLocationManager()
#Published var lastSearchedCity = ""
var hasFoundOnePlacemark:Bool = false
func checkIfLocationServicesIsEnabled(){
DispatchQueue.global().async {
if CLLocationManager.locationServicesEnabled(){
self.locationManager.delegate = self
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest/// kCLLocationAccuracyBest is the default
self.checkLocationAuthorization()
}else{
// show message: Services desabled!
}
}
}
private func checkLocationAuthorization(){
switch locationManager.authorizationStatus{
case .notDetermined:
locationManager.requestWhenInUseAuthorization()
case .restricted:
// show message
case .denied:
// show message
case .authorizedWhenInUse, .authorizedAlways:
/// app is authorized
locationManager.startUpdatingLocation()
default:
break
}
}
func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) {
checkLocationAuthorization()
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
hasFoundOnePlacemark = false
CLGeocoder().reverseGeocodeLocation(manager.location!, completionHandler: {(placemarks, error)-> Void in
if error != nil {
self.locationManager.stopUpdatingLocation()
// show error message
}
if placemarks!.count > 0 {
if !self.hasFoundOnePlacemark{
self.hasFoundOnePlacemark = true
let placemark = placemarks![0]
self.lastSearchedCity = placemark.locality ?? ""
}
self.locationManager.stopUpdatingLocation()
}else{
// no places found
}
})
}
}
SearchManagerViewModel Class
class SearchManagerViewModel: ObservableObject{
#Published var cityName = "" // use this directly in SwifUI views
#ObservedObject private var locationManager = LocationManager()
// Call this directly fron onAppear in SwiftUI views
// This method is more complex than what is shown here. It handles other things like HTTP requests etc.
func searchAndSetCity(){
locationManager.checkIfLocationServicesIsEnabled()
self.cityName = locationManager.lastSearchedCity
}
}
ContentView.swift
struct ContentView: View {
#StateObject private var searchManager = SearchManagerViewModel()
var body: some View {
VStack {
Text(searchManager.cityName)
.font(.callout)
}
.onAppear{
searchManager.searchAndSetCity()
}
}
}
So I am dealing with an issue where the LocationManager file that I have, and the didUpdateLocations function, is being called multiple times on application startup and I can't figure out what is causing it.
So I have the following LocationManager:
import Foundation
import CoreLocation
import MapKit
final class LocationManager: NSObject, ObservableObject, CLLocationManagerDelegate {
#Published var userLocation: CLLocation?
#Published var defaultRegion: MKCoordinateRegion?
#objc static let getInstance = LocationManager()
private let locationManager = CLLocationManager()
override init() {
super.init()
locationManager.delegate = self
log.info("\n 🟢: (LocationManager) - Initialize Location Services inside init()")
}
func startUpdatingLocation() {
locationManager.delegate = self
locationManager.requestWhenInUseAuthorization()
locationManager.startUpdatingLocation()
}
func requestLocation() {
locationManager.requestLocation()
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
guard let location = locations.last else { return }
DispatchQueue.main.async {
self.userLocation = location
log.info("\n 🟡: (LocationManager) - Setup new location as: \(location)")
self.defaultRegion = MKCoordinateRegion(center: location.coordinate, span: USER_LOCATION_SPAN)
log.info("\n 🟡: (LocationManager) - Setup default region as \(location.coordinate.latitude) and \(location.coordinate.longitude).")
self.locationManager.stopUpdatingLocation()
log.info("\n 🟡: (LocationManager) - Stop updating the location.")
}
}
}
Then I am utilizing it in two separate view files called MapUIView and MapUIView2 and I have the following object in both:
#ObservedObject var locationManager = LocationManager.getInstance
This causes the DispatchQueue.main.async inside didUpdateLocations to run through twice on application start - Is this normal behavior or is it possible to have the didUpdateLocations to run just once, but handle multiple views?
I have an app built using SwiftUI that works with user location. Using online tutorials, I have come up with a class LocationManager that handles the request using the delegate method and has an attribute #Published that sets the location as soon as it receives it.
I also have a ViewModel that has a function getData(location: CLLocation) that will properly update my view after an async call to a different API.
My question is, what is the best way to connect the LocationManager with the ViewModel, so that as soon as the LocationManager gets the location using the delegate it automatically calls the getData() function with that value?
I've tried to come up with a few solutions on my own, such as passing a closure to the LocationManager to call viewModel.getData() when the delegate is updated, but I got an issue with the "closure capturing a mutating self parameter". Any help would be greatly appreciated!!
Here is the code in question:
final class LocationManager: NSObject, ObservableObject {
#Published var location: CLLocation?
private let locationManager = CLLocationManager()
override init() {
super.init()
locationManager.requestWhenInUseAuthorization()
locationManager.startUpdatingLocation()
locationManager.delegate = self
}
}
extension LocationManager: CLLocationManagerDelegate {
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
guard let location = locations.last else {
return
}
DispatchQueue.main.async {
self.location = location
}
}
}
class ViewModel: ObservableObject {
#Published dataArray = [Model]()
func getData(location: CLLocation) {
// async api call
// update dataArray for view in completion handler
}
}
struct ShowData: View {
// initialize LocationManager
#StateObject var locationManager = LocationManager()
// initialize ViewModel
#StateObject var viewModel = ViewModel()
var body: some View {
// show dataArray
}
}
You can own the LocationManager in your view model:
class ViewModel: ObservableObject {
#Published dataArray = [Model]()
var lm = LocationManager()
}
Then, you could architect the LocationManager to take a separate delegate (which could be the view model), or, you could use Combine to listen for changes on the #Published property on the LocationManager:
cancellable = lm.$location.sink { ... }
I am using the following observable object to track the users location:
import Foundation
import MapKit
class LocationManager: NSObject, ObservableObject {
private let locationManager = CLLocationManager()
#Published var location: CLLocation? = nil
override init() {
super.init()
self.locationManager.delegate = self
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
self.locationManager.distanceFilter = kCLDistanceFilterNone
self.locationManager.requestWhenInUseAuthorization()
self.locationManager.startUpdatingLocation()
}
func locationServicesEnabled() -> Bool {
return self.locationManager.locationServicesEnabled()
}
}
extension LocationManager: CLLocationManagerDelegate {
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
guard let location = locations.last else {
return
}
self.location = location
}
}
However, when I try to compile I get an error next to the return self.locationManager.locationServicesEnabled() statement. The compiler says: Static member 'locationServicesEnabled' cannot be used on instance of type 'CLLocationManager', Replace 'self.locationManager' with 'CLLocationManager'. I do not understand this error because self.locationManager is an instance of CLLocationManager. Please help.
Static means that locationServicesEnabled is a member of the class, not of the object. Use the classname CLLocationManager as suggested.
Seems like the API has changed, earlier it was an instance method, now it is a class method:
https://developer.apple.com/documentation/corelocation/cllocationmanager/1620566-locationservicesenabled
static func configureLocationManager(manager: CLLocationManager, delegate: CLLocationManagerDelegate?) {
manager.allowsBackgroundLocationUpdates = true
manager.delegate = delegate
manager.desiredAccuracy = kCLLocationAccuracyThreeKilometers
switch manager.authorizationStatus {
case .authorizedAlways, .authorizedWhenInUse:
if CLLocationManager.locationServicesEnabled() {
manager.requestLocation()
}
default:
manager.requestWhenInUseAuthorization()
}
}
Here a piece of code that configured location manager and checks whether the app was allowed by user to use location services.
Here is more code that could be useful. This is a file that I created to implement the delegate methods.
https://github.com/aibo-cora/Safe-Bavaria/blob/main/Safe%20Bavaria/View%20Model%20-%20Utility/Find.User.Location.swift
i am trying to implement SwiftUI and CoreLocation with the MVVM-Pattern. My LocationManager as Helper works fine. But how I can change the properties of my LocationViewModel? I am implemented my #ObservedObject of the LocationManager in LocationViewModel. Here is my problem.
I don't have a idea to implement properties they change on the fly. Nothing is changed in my LocationView. By pressing a Button anything works fine one time. But the LocationViewModel must change there properties on every change of the LocationManager.
In summary I would like to display the current user position.
// Location Manager as Helper
import Foundation
import CoreLocation
class LocationManager: NSObject, ObservableObject {
let locationManager = CLLocationManager()
let geoCoder = CLGeocoder()
#Published var location: CLLocation?
#Published var placemark: CLPlacemark?
override init() {
super.init()
self.locationManager.delegate = self
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
self.locationManager.requestWhenInUseAuthorization()
self.locationManager.startUpdatingLocation()
}
func geoCode(with location: CLLocation) {
geoCoder.reverseGeocodeLocation(location) { (placemark, error) in
if error != nil {
print(error!.localizedDescription)
} else {
self.placemark = placemark?.first
}
}
}
}
extension LocationManager: CLLocationManagerDelegate {
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
guard let location = locations.first else { return }
DispatchQueue.main.async {
self.location = location
self.geoCode(with: location)
}
}
func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
// TODO
}
}
// Location Model
import Foundation
import CoreLocation
struct Location {
var location: CLLocation = CLLocation()
var placemark: CLPlacemark = CLPlacemark()
}
// Location View Model
import SwiftUI
import CoreLocation
class LocationViewModel: ObservableObject {
#ObservedObject var locationManager: LocationManager = LocationManager()
#Published var location: Location
init() {
self.location = Location()
}
}
// Location View
import SwiftUI
struct LocationView: View {
#ObservedObject var locationViewModel: LocationViewModel = LocationViewModel()
var body: some View {
VStack(alignment: .leading) {
Text("Latitude: \(self.locationViewModel.location.location.coordinate.latitude.description)")
Text("Longitude: \(self.locationViewModel.location.location.coordinate.longitude.description)")
}
}
}
struct LocationView_Previews: PreviewProvider {
static var previews: some View {
LocationView()
}
}
Update
Now, I have set up my MapView.
But how I can receive the data of my LocationManager? The didUpdateLocations method is working in LocationManager.
All what I am trying to do goes wrong. I would like to set the region on my MapView based on the current user location. In UIKit it was very simple, but in SwiftUI it is freaky.
// Map View
import SwiftUI
import MapKit
struct MapView: UIViewRepresentable {
#ObservedObject var locationManager: LocationManager = LocationManager()
class Coordinator: NSObject, MKMapViewDelegate {
var parent: MapView
init(_ control: MapView) {
self.parent = control
}
}
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
func makeUIView(context: Context) -> MKMapView {
let mapView = MKMapView(frame: .zero)
mapView.delegate = context.coordinator
return mapView
}
func updateUIView(_ mapView: MKMapView, context: Context) {
mapView.showsUserLocation = true
}
}
struct MapView_Previews: PreviewProvider {
static var previews: some View {
MapView()
}
}
SwiftUI 2
Use instead StateObject in this case
struct LocationView: View {
#StateObject var locationManager: LocationManager = LocationManager()
...
SwiftUI 1
Actually LocationViewModel is redundant here. As your LocationManager is a ObservableObject you can use it directly in your view, as below:
struct LocationView: View {
#ObservedObject var locationManager: LocationManager = LocationManager()
var body: some View {
VStack(alignment: .leading) {
Text("Latitude: \(locationManager.location.coordinate.latitude.description)")
Text("Longitude: \(locationManager.location.coordinate.longitude.description)")
}
}
}