如何等待嵌套的Alamofire请求完成

Question

我有两个Alamofire请求。两者都可以自行工作。

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) 

} 

而且......

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") 

    }) 
} 

上面的代码将无法工作，因为 “getPatientID” 功能是不完整的。我知道我知道我必须以某种方式使用派遣或完成处理程序。但我觉得这个话题非常混乱。我在这里查看了类似的解决方案，但找不到适用于我的解决方案。

Answer 1

您可以嵌套调用postPDF的getPatientID完成处理程序中是这样的：

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) 

} 

Answer 2

您可以添加完成处理您getPatientId功能。

func getPatientID(completion: (id: String?) -> Void) { //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!) 
        } 
       } 
       completion(patientID) 
      }) 

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

    view.endEditing(true) 
} 

而且

func postPDF() { 
    getPatientID() { 
     patientID in 
     //WILL WAIT FOR COMPLETION 

     // Make sure to handle error conditions. 
     // patientID could be nil 

     // rest of code here 

    } 
}