import Foundation
import IOKit.pwr_mgt

var assertionID : IOPMAssertionID = IOPMAssertionID(0)
var description : CFString = "Cup of coffee" as CFString

let success = IOPMAssertionDeclareUserActivity(description, kIOPMUserActiveLocal, &assertionID)
if success == kIOReturnSuccess {
    // IOPMAssertionRelease(assertionID)
}