How to range iBeacons(swift 3.0, xcode8.1, Beacon)

BLE Beacons
1

Hi, all.

I want to range beacons.
I have iBeacons, but didRangeBeacon method’s beacons: [CLBeacon] count is 0.
Please help me.

My code is below.
(swift 3.0, xcode 8.1)

class BeaconListViewController: UIViewController {
    private let manager = ESTBeaconManager()
    let beaconRegion = CLBeaconRegion(proximityUUID: UUID(uuidString: "B9407F30-F5F8-466E-AFF9-25556B57FE6D")!, identifier: "ranged region")
    
    override func viewDidLoad() {
        super.viewDidLoad()
        manager.delegate = self
        manager.requestAlwaysAuthorization()
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        manager.startRangingBeacons(in: beaconRegion)
    }
    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        manager.stopRangingBeacons(in: beaconRegion)
    }
}

extension BeaconListViewController: ESTBeaconManagerDelegate {
    func beaconManager(_ manager: Any, didRangeBeacons beacons: [CLBeacon], in region: CLBeaconRegion) {
        if beacons.count == 0 {
            print("not found")
        } else {
            beacons.forEach({ (beacon: CLBeacon) in
                print("beacon major, minor, rssi = %@, %@, %d", beacon.major.stringValue, beacon.minor.stringValue, beacon.rssi)
            })
        }
    }
}