How to setup a "Check-In" alert using Geofencing and CLCircularRegion?

Question

I'm trying to set up an alert that once a user enters a specific location the alert pops up and allows users to "Check-in". After the user checks in the app then notifies an api endpoint that the user successfully checked in. This is my first time working with geofencing and corelocation. I get the basic idea of how to set it up but am not entirely sure how the check-in alert and geofence tie together. Here is my code:

import UIKit
import CoreLocation

class ViewController: UIViewController, CLLocationManagerDelegate{


  var manager = CLLocationManager()


  override func viewDidLoad() {
    super.viewDidLoad()


    // Core Location
    manager.delegate = self
    manager.desiredAccuracy = kCLLocationAccuracyBest
    manager.requestWhenInUseAuthorization()
    manager.startUpdatingLocation()


    var latitude: CLLocationDegrees = 43.039278
    var longitude: CLLocationDegrees = -87.932479
    var center: CLLocationCoordinate2D = CLLocationCoordinate2DMake(latitude, longitude)
    var radius: CLLocationDistance = CLLocationDistance(10.0)
    var identifier: String = "storeID"

    var geoRegion: CLCircularRegion = CLCircularRegion(center: center, radius: radius, identifier: identifier)

  }


  func showSimpleAlertWithTitle(title: String!, message: String!, viewController: UIViewController) {
    let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert)
    let action = UIAlertAction(title: "Check-In", style: .Cancel , handler: nil)
    alert.addAction(action)
    viewController.presentViewController(alert, animated: true, completion: nil)
  }


}

Answer 1

1. Set notifyOnEntry = true on the CLCircularRegion to be notified when entering or exiting the region.
2. Implement locationManager:didEnterRegion: delegate method to handle the event.

Example:

override func viewDidLoad() {
    super.viewDidLoad()


    manager.delegate = self
    manager.desiredAccuracy = kCLLocationAccuracyBest
    manager.requestWhenInUseAuthorization()
    manager.startUpdatingLocation()

    var latitude: CLLocationDegrees = 43.039278
    var longitude: CLLocationDegrees = -87.932479
    var center: CLLocationCoordinate2D = CLLocationCoordinate2DMake(latitude, longitude)
    var radius: CLLocationDistance = CLLocationDistance(10.0)
    var identifier: String = "storeID"

    var geoRegion: CLCircularRegion = CLCircularRegion(center: center, radius: radius, identifier: identifier)
    geoRegion.notifyOnEntry = true

    manager.startMonitoringForRegion(geoRegion)
}


func locationManager(_ manager: CLLocationManager, didEnterRegion region: CLRegion) {

    showSimpleAlertWithTitle("Entered region \(region.identifier)", message: nil)
}

func showSimpleAlertWithTitle(title: String!, message: String!) {
    let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert)
    let action = UIAlertAction(title: "Check-In", style: .Cancel , handler: nil)
    alert.addAction(action)
    presentViewController(alert, animated: true, completion: nil)
  }

See: CLRegion.notifyOnEntry