How to do two concurrent API calls in swift

two concurrent API calls

func downloadDetails(){
    let dispatchGroup = DispatchGroup()

    dispatchGroup.enter()   // <<---
    WebServiceManager.getAData(format:A, withCompletion: {(data: Any? , error: Error?) -> Void in

        if let success = data {

            DispatchQueue.main.async {
                (success code)
                dispatchGroup.leave()   // <<----
            }
        }
    })

    dispatchGroup.enter()   // <<---
    webServiceManager.getBData(format: B, withCompletion: {(data: Any? , error: Error?) -> Void in

        if let success = data {

            DispatchQueue.main.async {
               (success code)
               dispatchGroup.leave()   // <<----
            }
        }
    })

    dispatchGroup.notify(queue: .main) {
        // whatever you want to do when both are done
    }
}