BluetoothState.swift

import UIKit
import CoreBluetooth

enum BluetoothState: CustomStringConvertible {
    case off, on, unknown

    init(bluetoothState: CBManagerState) {
        switch bluetoothState {
        case .poweredOff: self = .off
        case .poweredOn: self = .on
        default: self = .unknown
        }
    }

    var description: String {
        switch self {
        case .off: return "Turned off"
        case .on: return "Turned on"
        case .unknown: return "Unknown"
        }
    }

    var color: UIColor {
        switch self {
        case .off: return .red
        case .on: return .green
        case .unknown: return .yellow
        }
    }
}

// MARK: - Case properties

extension BluetoothState {

    var off: BluetoothState? {
        guard case .off = self else {
            return nil
        }
        return self
    }

    var on: BluetoothState? {
        guard case .on = self else {
            return nil
        }
        return self
    }

    var unknown: BluetoothState? {
        guard case .unknown = self else {
            return nil
        }
        return self
    }

}