UIImageView随着信标而变化

Question

我正在尝试使用以下代码更改视图控制器屏幕上的单个UIImageView。但它目前正在发挥作用。有人能指出我正确的方向吗？

var imageView = UIImageView()

let locationManager = CLLocationManager()
let region = CLBeaconRegion(proximityUUID: UUID(uuidString: "B9407F30-F5F8-466E-AFF9-25556B57FE6D")!, identifier: "Estimotes")

let images = [
    53219:  UIImage(named:"White Glyph 2"),
    59317:  UIImage(named:"White Glyph 3"),
    17068: UIImage(named:"White Glyph 4")
]


func locationManager(_ manager: CLLocationManager, didRangeBeacons beacons: [CLBeacon], in region: CLBeaconRegion) {
    let knownBeacons = beacons.filter{ $0.proximity != CLProximity.unknown }
    if (knownBeacons.count > 0) {
        let closestBeacon = knownBeacons[0] as CLBeacon
        self.imageView.image = self.images[closestBeacon.minor.intValue]!
    }
}