extension DispatchQueue {
static var userInteractive: DispatchQueue { return DispatchQueue.global(qos: .userInteractive) }
static var userInitiated: DispatchQueue { return DispatchQueue.global(qos: .userInitiated) }
static var utility: DispatchQueue { return DispatchQueue.global(qos: .utility) }
static var background: DispatchQueue { return DispatchQueue.global(qos: .background) }
func after(_ delay: TimeInterval, execute closure: @escaping () -> Void) {
asyncAfter(deadline: .now() + delay, execute: closure)
}
func syncResult<T>(_ closure: () -> T) -> T {
var result: T!
sync { result = closure() }
return result
}
}
