如何在swift 4中进行两个并发API调用

Question

在此先感谢您的帮助,我有两个API调用,两个都是并发的,任何调用都可以先成功(我不想按顺序调用),两个调用成功后,我必须停止我的活动指示器并重新加载我的tableView ,这是我的代码,但我不知道这是否正确以及如何重新加载我的tableView并停止我的活动指示器.

func downloadDetails(){
    let operationQueue: OperationQueue = OperationQueue()
    let operation1 = BlockOperation() {
    WebServiceManager.getAData(format:A, withCompletion: {(data: Any? , error: Error?) -> Void in

          if let success = data {
              DispatchQueue.main.async {
                  (success code)
              }
           }
        })

        let operation2 = BlockOperation() {
        webServiceManager.getBData(format: B, withCompletion: {(data: Any? , error: Error?) -> Void in

                if let success = data {
                    DispatchQueue.main.async {
                       (success code)
                    }
                }
            })
        }
        operationQueue.addOperation(operation2)
    }
    operationQueue.addOperation(operation1)
}
downloadDetails() "calling function"

Answer 1

这正是用例DispatchGroup.输入每个呼叫的组,在呼叫结束时离开组,并在完成所有操作后添加通知处理程序.不需要单独的操作队列; 这些都是异步操作.

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
    }
}