ios - 如何等待嵌套的 Alamofire 请求完成

Question

我有两个 Alamofire 请求。两者都可以自己正常工作。

func getPatientID() {  //puts patientID into patientID variable

    UsingOauth2(drChronoOauth2Settings, performWithToken: { token in
        Router.OAuthToken = token
        apiCallText = "last_name=" + self.lastName.text! + "&"  + "first_name=" + self.firstName.text!
        Alamofire.request(Router.GetPatientsWithFilter())
            .responseJSON(completionHandler: { (result) -> Void in
                if let data = result.data {
                    let response = NSString(data: data, encoding: NSUTF8StringEncoding)
                    self.result.text = "\(response)"

                    json = JSON(data: data)
                }

                    self.result.text = ""
                    if json!["count"].intValue > 1 {
                        self.result.text = "more than one patient"
                        patientID = "-1"
                    } else {
                        for item in json!["results"].arrayValue {
                            patientID = item["id"].stringValue
                            self.result.text = ("Patient ID is: " + patientID!)
                    }
                }

            })

        }, errorHandler: {
            print("Oauth2 failed")

    })

view.endEditing(true)

}

还有……

func postPDF() {

    getPatientID()  //NEED TO WAIT FOR COMPLETION


    UsingOauth2(drChronoOauth2Settings, performWithToken: { token in
        DrChronoRequestConvertible.OAuthToken = token

        Alamofire.upload(
            .POST,
            "https://drchrono.com/api/documents",
            headers: ["Authorization" : "Bearer " +  token],
            multipartFormData: { multipartFormData in

               //some multiform data including patientID from getPatientID()

            },
            encodingCompletion: { encodingResult in
                switch encodingResult {
                case .Success(let upload, _, _):
                    upload.responseJSON { response in
                        debugPrint(response)
                        self.result.text = "Successful Upload"
                    }
                case .Failure(let encodingError):
                    print(encodingError)
                }
            }
        )            }, errorHandler: {
            print("Oauth2 failed")

    })
}

以上代码将无法运行，因为“getPatientID”函数未完成。我知道我知道我必须以某种方式使用调度或完成处理程序。但我觉得这个话题很困惑。我在这里查看了类似的解决方案，但找不到适合我的解决方案。

Answer 1

您可以将 postPDF 调用嵌套在 getPatientID 的完成处理程序中，如下所示:

func getPatientID() {  //puts patientID into patientID variable

UsingOauth2(drChronoOauth2Settings, performWithToken: { token in
    Router.OAuthToken = token
    apiCallText = "last_name=" + self.lastName.text! + "&"  + "first_name=" + self.firstName.text!
    Alamofire.request(Router.GetPatientsWithFilter())
        .responseJSON(completionHandler: { (result) -> Void in
            if let data = result.data {
                let response = NSString(data: data, encoding: NSUTF8StringEncoding)
                self.result.text = "\(response)"

                json = JSON(data: data)
            }

                self.result.text = ""
                if json!["count"].intValue > 1 {
                    self.result.text = "more than one patient"
                    patientID = "-1"
                } else {
                    for item in json!["results"].arrayValue {
                        patientID = item["id"].stringValue
                        self.result.text = ("Patient ID is: " + patientID!)
                }
            }

            // Now that getPatientID has completed, call the next function
            postPDF()

        })

    }, errorHandler: {
        print("Oauth2 failed")

})

view.endEditing(true)

}