I am pretty new with swfit and object c. I am not sure how to use the interface from 3rd party library request to place an order. Can anyone explain to me how can I build a make a reqeust as following async code?

placeOrder(with: <orderRequest!>, completion: <((orderResponse?, (any Error)?) -> Void)!((orderResponse?, (any Error)?) -> Void)!(orderResponse?, (any Error)?) -> Void>)