BaseGeolocable example

BaseGeolocable.swift

//
//  BaseGeolocable.swift
//
//  Created by Juan Felipe Alvarez Saldarriaga on 11/11/16.
//

import Foundation
import CoreLocation

protocol BaseGeolocable: class, CLLocationManagerDelegate {

  var currentLocation: CLLocation? { get set }
}

// MARK: - CLLocationManagerDelegate

extension BaseGeolocable {

  func defaultLocationManager() -> CLLocationManager {
    let manager = CLLocationManager()
    manager.distanceFilter = kCLDistanceFilterNone
    manager.desiredAccuracy = kCLLocationAccuracyThreeKilometers
    manager.delegate = self
    manager.requestWhenInUseAuthorization()

    return manager
  }

  func setCurrentLocationWith(manager: CLLocationManager, locations: [CLLocation], completion: (() -> Void)? = nil) {
    guard let newLocation = locations.last else {
      return
    }

    // see: http://stackoverflow.com/a/12848776/255463
    //
    // test the age of the location measurement to determine if the measurement is cached
    // in most cases you will not want to rely on cached measurements
    let locationAge = -newLocation.timestamp.timeIntervalSinceNow
    if locationAge > 5.0 {
      return
    }

    // test that the horizontal accuracy does not indicate an invalid measurement
    if newLocation.horizontalAccuracy < 0 {
      return
    }

    // test the measurement to see if it is more accurate than the previous measurement
    if currentLocation == nil || (currentLocation?.horizontalAccuracy)! > newLocation.horizontalAccuracy {
      // store the location as the "best effort"
      currentLocation = newLocation

      // test the measurement to see if it meets the desired accuracy
      //
      // IMPORTANT!!! kCLLocationAccuracyBest should not be used for comparison with location coordinate or altitidue
      // accuracy because it is a negative value. Instead, compare against some predetermined "real" measure of
      // acceptable accuracy, or depend on the timeout to stop updating. This sample depends on the timeout.
      //
      if newLocation.horizontalAccuracy <= manager.desiredAccuracy {
        // we have a measurement that meets our requirements, so we can stop updating the location
        //
        // IMPORTANT!!! Minimize power usage by stopping the location manager as soon as possible.
        //
        manager.stopUpdatingLocation()
      }
    }

    if let completion = completion {
      completion()
    }
  }
}

ServiceLocationViewController.swift

//
//  ServiceLocationViewController.swift
//
//  Created by Juan Felipe Alvarez Saldarriaga on 10/27/16.
//

import UIKit
import CoreLocation

final class ServiceLocationViewController: UIViewController {

  lazy var locationManager: CLLocationManager = self.defaultLocationManager()
  
  var viewModel: ServiceLocationViewModelProtocol? {
    willSet {
      viewModel?.viewDelegate = nil
    }

    didSet {
      viewModel?.viewDelegate = self
    }
  }

  override func viewDidLoad() {
    super.viewDidLoad()

    locationManager.startUpdatingLocation()
  }
}

// MARK: - Load

extension ServiceLocationViewController {

  func loadGeolocation() {
    guard let currentLocation = currentLocation else {
      return
    }

    viewModel?.currentLocation = currentLocation
    viewModel?.geolocationParentType = .service
    viewModel?.geolocation()
  }
}
 
// MARK: - BaseGeolocable

extension ServiceLocationViewController: BaseGeolocable {

  func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
    // FIXME: implement geolocable error (jf)
  }

  func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    self.setCurrentLocationWith(manager: manager, locations: locations, completion: { [unowned self] in
      self.loadGeolocation()
    })
  }
}