Swift2 didRangeBeacons never called - swift

Question

I'm trying to implement a dedicated class to scan for a specific iBeacon (in foreground and in background) but the function didRangeBeacons is never called.
I also set the parameter NSLocationAlwaysUsageDescription in my info.plist.
here is the class I developed:
class iBeacon: NSObject, UIApplicationDelegate, CLLocationManagerDelegate {
var locationManager: CLLocationManager!
var beaconRegion:CLBeaconRegion!
override init(){
super.init()
print("init...")
let uuidString = "B737D0E7-AF53-9B83-E5D2-922140A91234"
let beaconIdentifier = "nbuit-06B908"
let beaconUUID:NSUUID = NSUUID(UUIDString: uuidString)!
beaconRegion = CLBeaconRegion(proximityUUID: beaconUUID,
identifier: beaconIdentifier)
beaconRegion.notifyOnEntry = true
locationManager = CLLocationManager()
locationManager.delegate = self
if(locationManager!.respondsToSelector("requestAlwaysAuthorization")) {
locationManager!.requestAlwaysAuthorization()
}
locationManager!.pausesLocationUpdatesAutomatically = false
locationManager!.startMonitoringForRegion(beaconRegion)
locationManager!.startRangingBeaconsInRegion(beaconRegion)
locationManager!.startUpdatingLocation()
}
func sendLocalNotificationWithMessage(message: String!) {
let notification:UILocalNotification = UILocalNotification()
notification.alertBody = message
UIApplication.sharedApplication().scheduleLocalNotification(notification)
}
func locationManager(manager: CLLocationManager!, didStartMonitoringForRegion region: CLRegion!){
locationManager.requestStateForRegion(region)
}
func locationManager(manager: CLLocationManager!, didDetermineState state: CLRegionState, forRegion region: CLRegion!) {
if state == CLRegionState.Inside {
locationManager.startRangingBeaconsInRegion(beaconRegion)
}
else {
locationManager.stopRangingBeaconsInRegion(beaconRegion)
}
}
func locationManager(manager: CLLocationManager,
didRangeBeacons beacons: [CLBeacon],
inRegion region: CLBeaconRegion) {
print("didRangeBeacons");
var message:String = ""
if(beacons.count > 0) {
let nearestBeacon:CLBeacon = beacons[0] as! CLBeacon
switch nearestBeacon.proximity {
case CLProximity.Far:
message = "You are far away from the beacon"
case CLProximity.Near:
message = "You are near the beacon"
case CLProximity.Immediate:
message = "You are in the immediate proximity of the beacon"
case CLProximity.Unknown:
return
}
} else {
message = "No beacons are nearby"
}
print("%#", message)
sendLocalNotificationWithMessage(message)
}
func locationManager(manager: CLLocationManager!, didEnterRegion region: CLRegion!) {
print("Beacon in range")
}
func locationManager(manager: CLLocationManager!, didExitRegion region: CLRegion!) {
print("No beacons in range")
}
func locationManager(manager: CLLocationManager!, monitoringDidFailForRegion region: CLRegion!, withError error: NSError!) {
print("Failed monitoring region: \(error.description)")
}
func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) {
print("Location manager failed: \(error.description)")
}
}
I'm not able to find the reason why my iBeacon is not detected. I also checked for the UUID and name in a BLE scanner app and it seems to be correct.
If you have any idea to help me that would be great.
EDIT:
I Finally found the reason why the LocationManager was never started, I was instantiating my class like this:
let qualityOfServiceClass = DISPATCH_QUEUE_PRIORITY_DEFAULT
let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
dispatch_async(backgroundQueue, {
print("Running beacon detection in the background queue")
beaconSharedInstance
})
I was expecting to get this instance running in background, but by simply calling my instance like this
beaconSharedInstance
it starts and scans for regions correctly. but as soon as my app is inactive, I have the following log:
Ending background task
and my app stops scanning. I set the following parameters
locationManager.allowsBackgroundLocationUpdates = true
and also set Background Mode capability of my project.
any idea why my instance is stopped when the app is in background ?