Proximity sensor in Swift (from Objective-C)

Swift 3 Version

(Based on Eric Aya's answer)

func setProximitySensorEnabled(_ enabled: Bool) {
    let device = UIDevice.current
    device.isProximityMonitoringEnabled = enabled
    if device.isProximityMonitoringEnabled {
        NotificationCenter.default.addObserver(self, selector: #selector(proximityChanged), name: .UIDeviceProximityStateDidChange, object: device)
    } else {
        NotificationCenter.default.removeObserver(self, name: .UIDeviceProximityStateDidChange, object: nil)
    }
}

func proximityChanged(_ notification: Notification) {
    if let device = notification.object as? UIDevice {
        print("\(device) detected!")
    }
}

Here's my take on this.

func activateProximitySensor() {
    let device = UIDevice.currentDevice()
    device.proximityMonitoringEnabled = true
    if device.proximityMonitoringEnabled {
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "proximityChanged:", name: "UIDeviceProximityStateDidChangeNotification", object: device)
    }
}

func proximityChanged(notification: NSNotification) {
    if let device = notification.object as? UIDevice {
        println("\(device) detected!")
    }
}