{"id":1554,"date":"2015-06-07T10:37:01","date_gmt":"2015-06-07T16:37:01","guid":{"rendered":"http:\/\/dev.iachieved.it\/iachievedit\/?p=1554"},"modified":"2015-06-07T10:37:01","modified_gmt":"2015-06-07T16:37:01","slug":"writing-an-ibeacon-app-in-swift","status":"publish","type":"post","link":"https:\/\/dev.iachieved.it\/iachievedit\/writing-an-ibeacon-app-in-swift\/","title":{"rendered":"Writing an iBeacon App in Swift"},"content":{"rendered":"

Editor’s Note:<\/b> This is Part Two of our series of articles on creating a Swift iBeacon<\/a> application. By the end of the series<\/i> you will have written a “game” in Swift called You’re Getting Warmer!<\/i> which allows you to track down and find a beacon. Part One<\/a> gets you up and running iBeacon with a Gimbal Proximity Beacon Series 10.<\/p>\n

Before getting started with Part Two, you should have an operating iBeacon and know its UUID. If you don’t have an iBeacon start with Part One<\/a> of this series!<\/p>\n

If you’re working with iBeacon we’re just going to assume you known how to create a new Single View Application<\/b> Swift project with Xcode. Go ahead and do that now. We named our project gettingwarmer<\/code>.<\/p>\n

\"gettingwarmer_xcodeproj\"<\/a><\/center><\/p>\n

Beacon Ranging<\/h3>\n

There are two methods of listening for iBeacons in iOS: monitoring<\/i> and ranging<\/i>. The difference between the two is that monitoring<\/i> is an activity that can continue running in the background, while ranging<\/i> is a foreground activity. Radius Networks wrote up a nice explanation<\/a> describing the differences in detail. Apple’s iBeacon documentation<\/a> uses the term ranging<\/i> to describe the activity of determining the proximity of a given iBeacon. Our first application will make use of ranging as opposed to monitoring.<\/p>\n

BeaconManager<\/h3>\n

I have always preferred to use the singleton “manager” pattern for working with CoreLocation in iOS. We’ll create a class called BeaconManager<\/code> which will be responsible for an instance of CLLocationManager<\/code> as well as serving as our CLLocationManager<\/code> delegate. To get started create a new file BeaconManager.swift<\/code> in your gettingwarmer<\/code> Xcode project and add the following implementation:<\/p>\n

\r\nimport Foundation\r\nimport CoreLocation\r\n\r\nclass BeaconManager : NSObject, CLLocationManagerDelegate {\r\n  \r\n  static let sharedInstance = BeaconManager()\r\n  \r\n  var locationManager:CLLocationManager\r\n  \r\n  override init() {\r\n    self.locationManager = CLLocationManager()\r\n    \r\n    super.init()\r\n    \r\n    self.locationManager.delegate = self\r\n    self.locationManager.requestWhenInUseAuthorization()\r\n    \r\n  }\r\n  \r\n  func startRanging() {\r\n  }\r\n  \r\n  \/\/ MARK:  CLLocationManagerDelegate methods\r\n  func locationManager(manager: CLLocationManager!,\r\n                       didChangeAuthorizationStatus status: CLAuthorizationStatus) {\r\n  }\r\n  \r\n  func locationManager(manager: CLLocationManager!,\r\n                       didRangeBeacons beacons: [AnyObject]!,\r\n                       inRegion region: CLBeaconRegion!) {\r\n\r\n  }\r\n  \r\n  \r\n}\r\n<\/pre>\n
The class declaration and init<\/code> routine should be self-explanatory.  If you haven’t been working with Swift 1.2 you may have missed the introduction of the static<\/code> keyword which allows for a quick implementation of the singleton pattern.<\/p>\n
Let’s first implement the didChangeAuthorizationStatus<\/code> method, because once we are authorized we want to start ranging.<\/p>\n
Here’s our implementation:<\/p>\n
\r\n  \/\/ MARK:  CLLocationManagerDelegate methods\r\n  func locationManager(manager: CLLocationManager!,\r\n    didChangeAuthorizationStatus status: CLAuthorizationStatus) {\r\n      switch status {\r\n      case .NotDetermined:\r\n        self.locationManager.requestWhenInUseAuthorization()\r\n      case .AuthorizedWhenInUse, .AuthorizedAlways:\r\n        self.startRanging()\r\n      case .Denied, .Restricted:\r\n        NSNotificationCenter.defaultCenter().postNotificationName(\"LOCATION_DENIED\", object: nil)\r\n      default:\r\n        break\r\n      }\r\n  }\r\n<\/pre>\n
If the OS can’t determine the authorization status (.NotDetermined<\/code>), we’ll simply ask for it again (why not).<\/p>\n
If we receive a callback that our status is .AuthorizedWhenInUse<\/code> (what we requested) or .AuthorizedAlways<\/code> (which will never be the case), we’ll call our startRanging<\/code> method.<\/p>\n
If on the other hand we receive .Denied<\/code> or .Restricted<\/code>, we’ll broadcast a notification with NSNotificationCenter<\/code> that will be heard by our ViewController<\/code>.  The ViewController<\/code> will then be responsible for raising a dialog indicating that location services are required for the app to operate properly.<\/p>\n
Now, let’s take a look at our startRanging<\/code> method.<\/p>\n
\r\n  func startRanging() {\r\n    \r\n    let uuid   = NSUUID(UUIDString:\"788FA98B-871C-4C71-9944-88ADEC84A8DA\")\r\n    let region = CLBeaconRegion(proximityUUID: uuid, identifier: \"\")\r\n    self.locationManager.startRangingBeaconsInRegion(region)\r\n    \r\n  }\r\n<\/pre>\n
Ranging begins with the startRangingBeaconsInRegion<\/code> method, and in our case a region<\/i> is identified as “being in the proximity of a beacon broadcasting a UUID of 788FA98B-871C-4C71-9944-88ADEC84A8DA”.  It’s that simple.  If iOS hears a beacon with this UUID, it is “in” that region.<\/p>\n
It may be confusing at first that a “region” in this context is not geographical.  Apple’s QuickHelp documentation explains it this way:  “A CLBeaconRegion object defines a type of region that is based on the device\u2019s proximity to a Bluetooth beacon, as opposed to a geographic location.<\/i>”<\/p>\n
Once ranging starts we have to be prepared to receive didRangeBeacons<\/code> calls on our CLLocationManager<\/code> delegate.  For now, we’ll add this implementation:<\/p>\n
\r\n  func locationManager(manager: CLLocationManager!,\r\n    didRangeBeacons beacons: [AnyObject]!,\r\n    inRegion region: CLBeaconRegion!) {\r\n      \r\n      let beaconsRanged = beacons as! [CLBeacon]!\r\n      \r\n      if let beacon = beaconsRanged.last {\r\n        println(\"Beacon ranged:  \\(beacon)\")\r\n      }\r\n  }\r\n<\/pre>\n
Before leaving ranging, it is important to draw the distinction between monitoring<\/i> for regions and ranging<\/i> beacons.  Monitoring can run in the background with notifications sent to your app when the registered CLBeaconRegion<\/code> is “entered” (that is, the beacon was heard).  Ranging is for finer proximity detection and can only be used while the application is in the foreground.  Again, reading the Radius Networks article<\/a> is useful.<\/p>\n
Rounding Out<\/h3>\n
Thus far we’ve implemented:<\/p>\n