A Combine location publisher for CLLocationManager.

CLLocationManager+Combine.swift

// Requirements: a NSLocationWhenInUseUsageDescription entry in Info.plist
// Usage:  @State var locator = CLLocationManager.publishLocation()
//           and
//         .onReceive(locator) { location in
// Improvements needed: Move requestWhenInUseAuthorization into its own publisher and perhaps have a combineLatest pipeline for both authorized and valid location.
//                      A configuration param to init(), e.g. so each manager can have the same distanceFilter.
    
import Foundation
import Combine
import CoreLocation

extension CLLocationManager {
    public static func publishLocation() -> LocationPublisher{
        return .init()
    }

    public struct LocationPublisher: Publisher {
        public typealias Output = CLLocation
        public typealias Failure = Never

        public func receive<S>(subscriber: S) where S : Subscriber, Failure == S.Failure, Output == S.Input {
            let subscription = LocationSubscription(subscriber: subscriber)
            subscriber.receive(subscription: subscription)
        }
        
        final class LocationSubscription<S: Subscriber> : NSObject, CLLocationManagerDelegate, Subscription where S.Input == Output, S.Failure == Failure{
            var subscriber: S
            var locationManager = CLLocationManager()
            
            init(subscriber: S) {
                self.subscriber = subscriber
                super.init()
                locationManager.delegate = self
            }

            func request(_ demand: Subscribers.Demand) {
                locationManager.startUpdatingLocation()
                locationManager.requestWhenInUseAuthorization()
            }
            
            func cancel() {
                locationManager.stopUpdatingLocation()
            }
            
            func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
                for location in locations {
                    _ = subscriber.receive(location)
                }
            }
        }
    }
}


// Tester
//
//import SwiftUI
//import CoreData
//import CoreLocation
//import Combine
//
//struct ContentView: View {
//
//    @State private var counter = 0
//    var body: some View {
//        VStack {
//            ContentView2()
//            Button("Malc \(counter)") {
//                counter += 1
//            }
//        }
//
//    }
//}
//
//struct ContentView2: View {
//    
//    @State var timer = Timer.publish(every: 1, on: .main, in:.common).autoconnect()
//    @State var locator = CLLocationManager.publishLocation()
//    @State private var counter = 0
//    @State var locationString = ""
//    var body: some View {
//        VStack {
//            Text("Hello, World! \(counter)")
//            Text("Location \(locationString)")
//        }
//        .onReceive(timer) { time in
////            if self.counter == 5 {
////                self.timer.upstream.connect().cancel()
////            } else {
////              //  print("The time is now \(time)")
////            }
//            self.counter += 1
//        }
//        .onReceive(locator) { location in
//            locationString = String(format: "%.5f,%.5f %@", location.coordinate.latitude, location.coordinate.longitude, location.timestamp.description)
//        }
//    }
//}

For my current purpose it's enough and a great starting point in any case. Thanks a lot!