Cannot use an array in AppDelegate in ViewController

Question

In the AppDelegate I have the next extension:

extension AppDelegate: CLLocationManagerDelegate {
    func locationManager(manager: CLLocationManager!,didRangeBeacons beacons: [AnyObject]!, inRegion region: CLBeaconRegion!) {
        let viewController:ViewController = window!.rootViewController as! ViewController
        viewController.beacons = beacons as! [CLBeacon]?

        NSLog("didRangeBeacons");
    }
}

And in the ViewController I do:

class ViewController: UIViewController {
    var beacons: [CLBeacon]?

    override func viewDidLoad() {
        super.viewDidLoad()

        if(beacons != nil){
            println(beacons![0])
        }
    }
}

And it doesn't print me anything. But it's not empty, an array. It prints in the logs didRangeBeacons. So, what is the problem and how can I access to it?

Answer 1

CLLocationManagerDelegate's method locationManager(manager:,didRangeBeacons beacons:, inRegion:) is an asynchronous call. Here you are trying to get the value of beacons in your ViewController on the viewDidLoad method.

It's possible that the method on the AppDelegate fires after the view controller's viewDidLoad does.

Check that viewDidLoad is not being called before locationManager(manager:,didRangeBeacons beacons:, inRegion:)