Proximity.swift

      let estimoteCloudCredentials = CloudCredentials(appID: "MYAPPID", appToken: "MYAPPTOKEN")

        proximityObserver = ProximityObserver(credentials: estimoteCloudCredentials, onError: { error in
            print("ProximityObserver error: \(error)")
        })

        let zone = ProximityZone(tag: "Tag1", range: ProximityRange(desiredMeanTriggerDistance: 10.0)!)
        zone.onEnter = { zoneContext in
            self.appdelegate.window?.makeToast("near \(zoneContext.tag)", duration: 3.0)
        }
        zone.onExit = { zoneContext in
            self.appdelegate.window?.makeToast("left \(zoneContext.tag)", duration: 3.0)
            }
        
        let zone1 = ProximityZone(tag: "Tag2", range: ProximityRange(desiredMeanTriggerDistance: 10.0)!)
        zone1.onEnter = { zoneContext in
            self.appdelegate.window?.makeToast("near \(zoneContext.tag)", duration: 3.0)
        }
        zone1.onExit = { zoneContext in
            self.appdelegate.window?.makeToast("left \(zoneContext.tag)", duration: 3.0)
            }

        proximityObserver.startObserving([zone,zone1])