day-075

Day 75: Project 22: Detect-A-Beacon, Part One

This day covers the second and final part of Project 22: Detect-A-Beacon in Hacking with Swift. You can follow along directly here.

📒 Field Notes

I previously created projects alongside Hacking with Swift in a separate repository. For 100 Days of Swift, however, I've been extending things further and adding my projects to this repo under each "Part One" folder.

With that in mind, Day 75 focuses on several specific topics:

• Requesting Location: Core Location
• Hunting the Beacon: CLBeaconRegion

Requesting Location: Core Location

Consent is important. Especially when it comes to location tracking. Given that our app is all about tracking its proximity to a beacon, however... we're going to need those permissions 🙂.

Specifically, we'll need to acquire the Privacy - Location When In Use Usage Description and Privacy - Location Always and When In Use Usage Description permissions. It seems like a bit much, but this configuration allows us to detect beacons in the background — while still allowing users to manually specify When In Use, either during our initial request, or later in Settings.

Hunting the Beacon: CLBeaconRegion

With an initializer that takes arguments for proximityUUID, major, minor, identifier, CLBeaconRegion allows us to describe the location and identity of a beacon at several levels of granularity.

Assuming the following...

• A beacon matching the information defined on our CLBeaconRegion is running on another device
• The device that our app is running on is capable of monitoring and ranging (measuring distance) beacons.
• Our app has permissions to read the current device location.

... we can tell our CLLocationManager instance to start monitoring and ranging:

locationManager.startMonitoring(for: beaconRegion)
locationManager.startRangingBeacons(in: beaconRegion)

From there, our CLLocationManagerDelegate can be set up to receive events such as didRangeBeacons, where we can infer our proximity to a ranged beacon:

func locationManager(
    _ manager: CLLocationManager,
    didRangeBeacons beacons: [CLBeacon],
    in region: CLBeaconRegion
) {
    let beaconProximity = beacons.first?.proximity ?? CLProximity.unknown

    updateUI(for: beaconProximity)
}