等待两个不同的REST /网络呼叫完成

Question

我正在使用REST进行大量调用，并决定将这些连接调用分离为一个单独的对象，从我的UI类中调用。这是我正在使用的功能，它不会等待请求完成。我不确定我做错了什么，并尝试使用堆栈和网络中的许多示例，包括：

Wait until swift for loop with asynchronous network requests finishes executing

Waiting until the task finishes

//let loader = from Oauth2/p2_OAuth2 pod to load JSON
func ConnectionHandler()
{

        let dg = DispatchGroup()

        switch self.RequestType
        {
        case aRequest:
            //if I make a single call here, works fine 
        case bRequest:
            //if I make a single call here, works fine 
        case abRequest:
            //when making requests for both type a and b, can’t get it to work
            dg.enter()

            loader.perform(request: self.userDataRequest)
            { response in
                do
                {
                    let json = try response.responseJSON()
                    self.structWrapper.aArray = self.loadAArray(dict: json)
                }
                catch let error {
                    self.didCancelOrFail(error)
                }
            }
            self.dexRequestType = DexRequestTypesEnum.glucoseValues
            //ignore last line.  should be removed.
            loader.perform(request: self.userDataRequest)
            { response in
                do
                {
                    let json = try response.responseJSON()
                    self.structWrapper.bArray = self.loadBArray(dict: json)                }
                catch let error {
                    self.didCancelOrFail(error)
                }
            }
            dg.leave()
            dg.notify(queue: .main) 
            {
                //will print, but requests are not complete, arrays are empty, even though breakpoints hit in loading them.
              for x in self.structWrapper.aArray                  
               {
                 print(x.displayTime + ":" + x.units)
               }
               for y in self.structWrapper.bArray
               {
                print(y.displayTime + ":" + String(y.someNumber) 
               }
                print(“tasks complete”)
             }

        }

    }

Answer 1

你必须使用

在调用Task

之前

dg.enter（） 任务完成后

dg.leave（）

就像那样：

return function() {
  localVar++;
  return localVar;
}