---
title: Ranging for Beacons
framework: corelocation
role: sampleCode
role_heading: Sample Code
path: corelocation/ranging-for-beacons
---

# Ranging for Beacons

Configure a device to act as a beacon and to detect surrounding beacons.

## Overview

Overview Beacons make location-based products and services available to users by broadcasting information to your device. Ranging is the process of reading the characteristics of a beacon region, such as signal strength, advertising interval, and measured power. This sample code project configures a device to act as a beacon, and configures a device to use ranging to find surrounding beacons. Use two iOS devices to run the sample, with one acting as a beacon, and the other ranging for the beacon. note: This project is associated with WWDC 2019 session 705: What’s New in Location. Configure a Device to Act as a Beacon Run the sample app on the first iOS device. Select the option to Configure a Beacon. The project hardcodes a default value for the UUID that can be changed in ConfigureBeaconViewController.swift. let beaconUUID = UUID(uuidString: "E2C56DB5-DFFB-48D2-B060-D0F5A71096E0") Optionally modify the major and minor value for the beacon, then select the Enabled switch on the configuration screen to start advertising. ConfigureBeaconViewController.swift contains a view controller object that configures the iOS device running this app to act as a beacon.  The configureBeaconRegion() method sets up the region and starts advertising itself. if peripheralManager.state == .poweredOn {     peripheralManager.stopAdvertising()     if enabled {         let bundleURL = Bundle.main.bundleIdentifier!                  // Defines the beacon identity characteristics the device broadcasts.         let constraint = CLBeaconIdentityConstraint(uuid: beaconUUID!, major: major, minor: minor)         region = CLBeaconRegion(beaconIdentityConstraint: constraint, identifier: bundleURL)                  let peripheralData = region.peripheralData(withMeasuredPower: nil) as? [String: Any]                  // Start broadcasting the beacon identity characteristics.         peripheralManager.startAdvertising(peripheralData)     } Configure a Device to Range for Beacons Using a second iOS device, run the sample app and tap Range for Beacons to scan for beacons. Add a UUID to range for by tapping the Add button in the upper corner of the screen. The hardcoded UUID appears by default. RangeBeaconViewController.swift contains a view controller object that ranges a set of beacon regions that the user adds. As in any location-based service, first request authorization. Use a CLLocationManager instance to request that authorization, set up the constraint based on the hardcoded UUID, then tell the instance to start monitoring. self.locationManager.requestWhenInUseAuthorization()

// Create a new constraint and add it to the dictionary. let constraint = CLBeaconIdentityConstraint(uuid: uuid) self.beaconConstraints[constraint] = []

/* By monitoring for the beacon before ranging, the app is more energy efficient if the beacon is not immediately observable. */ let beaconRegion = CLBeaconRegion(beaconIdentityConstraint: constraint, identifier: uuid.uuidString) self.locationManager.startMonitoring(for: beaconRegion) When the device enters the specified region, the locationManager(_ manager: CLLocationManager, didDetermineState state: CLRegionState, for region: CLRegion) delegate method receives the region state and starts ranging beacons. While one or more beacons are in range, the locationManager(_ manager: CLLocationManager, didRange beacons: [CLBeacon], satisfying beaconConstraint: CLBeaconIdentityConstraint) delegate method receives their characteristics in the passed array.

## See Also

### iBeacon

- [Determining the proximity to an iBeacon device](corelocation/determining-the-proximity-to-an-ibeacon-device.md)
- [Turning an iOS device into an iBeacon device](corelocation/turning-an-ios-device-into-an-ibeacon-device.md)
- [CLBeacon](corelocation/clbeacon.md)
- [CLCondition](corelocation/clcondition-swift.protocol.md)