LocationService

• locationSubject : 위치정보를 구독할 서브젝트
• locationManager : 위치 관리를 얘가 다한다
  • didUpdateLocation : 위치 정보가 들어있음
  • requestWhenInUseAuthorization : 위치 권한 허용 요청
  • didChangeAuthorization : 위치 권한 허용 여부 확인
• requestLocation : 위치 권한 허용 함수
• compactMap : nil 값을 버리고 값이 있을 때만 전달
• deffered : 옵저버블을 미리 만들지 않고, 구독을 시작되면 옵저버블을 만든다

class LocationService {
    static let shared = LocationService()
    let disposeBag = DisposeBag()
    
    let locationSubject = BehaviorSubject<CLLocationCoordinate2D?>(value: nil)
    let locationManager = {
        let locationManager = CLLocationManager()
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.distanceFilter = kCLDistanceFilterNone
        return locationManager
    }()
    
    private init() {
        self.locationManager.rx.didUpdateLocations
            .compactMap {$0.locations.last?.coordinate}
            .bind(to: locationSubject)
            .disposed(by: disposeBag)
        self.locationManager.startUpdatingLocation()
    }
    
    func requestLocation() -> Observable<CLAuthorizationStatus> {
        return Observable<CLAuthorizationStatus>
            .deferred { [weak self] in
                guard let ss = self else { return .empty() }
                ss.locationManager.requestWhenInUseAuthorization()
                return ss.locationManager.rx.didChangeAuthorization
                    .map { $1 }
                    .filter { $0 != .notDetermined }
                    .do(onNext: { _ in ss.locationManager.startUpdatingLocation() })
                    .take(1)
            }
    }
}