swift variable scope in closure wrt CLGeocoder() - swift

Question

Can someone please help me understand why in the following code will have output like this:
[<+37.49638550,-122.31160280> +/- 5.00m (speed 32.65 mps / course
294.26) # 7/27/16, 4:34:19 AM Eastern Daylight Time]
n/a Belmont Belmont
Belmont 1
That is, why the variable locality will have value "n/a" when printed at a specific point whereas localityVC & localityGlobal never do? Is this purely a scope issue or something to do with CLGeocoder()? Thanks
import UIKit
import MapKit
import CoreLocation
var localityGlobal: String = "n/a"
class ViewController: UIViewController, CLLocationManagerDelegate {
let locationManager = CLLocationManager()
var localityVC: String = "n/a"
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
print("hello")
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.requestWhenInUseAuthorization()
locationManager.startUpdatingLocation()
}
func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
print(locations)
let userLocation: CLLocation = locations[0]
var locality: String = "n/a"
CLGeocoder().reverseGeocodeLocation(userLocation, completionHandler: {(placemarks, error) -> Void in
if error != nil {
print("CLGeocoder.reverseGeocodeLocation() failed")
return
}
if placemarks!.count > 0 {
locality = placemarks![0].locality!
self.localityVC = placemarks![0].locality!
localityGlobal = placemarks![0].locality!
print(locality, placemarks!.count)
} else {
print("CLGeocoder.reverseGeocodeLocation() error in geocoder data")
}
})
print(locality, localityVC, localityGlobal)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
In order for the above to run you also need to have:
Build Phases -> Link Binary with Libraries include
CoreLocation.framework,
Info.plist must have variables
NSLocationWhenInUseUsageDescription and
NSLocationAlwaysUsageDescription set,
Simulator -> Debug -> Location set to something like Apple, City Bicycle Ride, City Run or Freeway Drive
I'm running xcode 7.3.1 (7D1014)

Answer 1

This isn't a scope issue, it's a timing one. You get n/a because the closure has yet to run when that print statement is executed.
The other variables are retaining the value from a prior call.