How to start a bluetooth connection?

To start a bluetooth peripheral searh on the Mac OS I did what exemplified below, but the switch falls into unsupported case.

What have I to do to turn on bluetooth?

class BTSearch: NSObject, CBCentralManagerDelegate
{
     override init()
     {
          super.init()
          centralManager = CBCentralManager(delegate: self, queue: nil)
     }
     func centralManagerDidUpdateState(_ central: CBCentralManager)
     {
          switch (central.state)
          {
          case .unsupported:
          case ...

          }
     }
}