Learn how to broadcast iBeacon signals from an iOS device.
- Core Location
Any iOS device that supports sharing data using Bluetooth low energy can be turned into an iBeacon. Apps that use their underlying iOS device as an iBeacon must run in the foreground. As a result, use this feature for point-of-sale apps or for apps that are meant to run in the foreground anyway. For other types of iBeacon implementations, use dedicated beacon hardware from third-party manufacturers. To use an iOS device as an iBeacon, you do the following:
Obtain or generate a 128-bit UUID for your device.
CLBeaconobject containing the UUID value along with appropriate major and minor values for your beacon.
Advertise the beacon information using the Core Bluetooth framework.
Get a UUID for Your Device
The primary way to identify an iBeacon is from its UUID. When deploying one or more beacons, you assign a UUID to each one that conveys the beacon’s purpose to clients. The exact purpose of a beacon is something you define. For example, a department store chain might use the same UUID for all of its deployed beacons, or each store might be assigned a different UUID. Because detection involves using region monitoring to look for beacons with specific UUIDs, using fewer UUIDs is easier to manage.
To create a new UUID for your iBeacon deployment, use the
uuidgen command-line tool. Open Terminal and type
uuidgen on the command line and press Return. This tool generates a unique 128-bit value and formats it as an ASCII string that is punctuated by hyphens, as shown in Listing 1.
Configure the CLBeaconRegion Object
CLBeacon object to configure your beacon’s identity. You use the beacon region to generate a dictionary of information that you can advertise later over Bluetooth. Listing 2 shows how to create a beacon region object and fill it with information.
The UUID, major, and minor values are specific to your iBeacon implementation. You decide the meaning of these values and decide how apps that detect your beacons interpret those values.
Advertise Your Beacon Over Bluetooth
To broadcast your beacon’s identity from an iOS device, use the Core Bluetooth framework to configure the iOS device as a Bluetooth peripheral. When configured as a peripheral, your iOS device broadcasts its beacon information out to other devices using the Bluetooth hardware. Other devices use that information to perform ranging and detect their proximity to your iOS device.
Add the Core Bluetooth framework to your Xcode project. In your code, create a
CBPeripheral object and call its
start method to begin broadcasting your beacon data. The
start method takes a dictionary parameter that contains your beacon information. Call the
peripheral method of the
CLBeacon that you created previously to get a dictionary containing the data associated with your beacon.
When calling the
peripheral method to obtain your data dictionary, you typically pass
nil to specify the default received signal strength indicator (RSSI) value associated with the iOS device. This parameter represents the signal strength (in decibels) measured from one meter away from the device. You can specify custom values if you need to calibrate the device for better ranging performance in certain environments.
When you create a peripheral manager object, it calls the
peripheral method of its delegate object. You must implement this delegate method to ensure that Bluetooth low energy is supported and available to use on the iOS device.
During ranging, there may be a brief period in which Core Location creates two
CLBeacon objects for the same iOS device. This behavior occurs because iOS changes the device’s Bluetooth identifier periodically to protect the user’s privacy, and one beacon represents the old identifier and one beacon represents the new identifier. Within 2 seconds of the identifier change, the beacon with the old identifier has its proximity property set to
unknown. Within 10 seconds, the beacon with the old identifier is no longer reported.