cloudkit回调系列--何时弹出到以前的控制器

Question

我有一系列连续的云工具包调用来获取记录，每个调用都是基于以前的fetch。这些获取中的任何一个都可能失败，然后我必须切换到以前的控制器。由于获取失败的地方太多，我不得不在许多位置将popViewController嵌入到以前的控制器中。如果可能的话，我可以避免这种情况，只打一次电话吗？

 func iCloudSaveMeterHubPrivateDbCz() {

    self.clOps.iCloudFetchRecord(recordName: locId, databaseScope: CKDatabaseScope.private, customZone: true, completion: { (locationRecord, error) in
       guard error == nil else {
             self.navigationController!.popViewController(animated: true)
            return
        }
        self.iCloudFetchMeter(withLocationCKRecord: locationRecord!) { records, error in
            if (error != nil ) {
                if let ckerror = error as? CKError {
                    self.aErrorHandler.handleCkError(ckerror: ckerror)
                }
                 self.navigationController!.popViewController(animated: true)
            }
            if let _ = records?.first {
                      self.clOps.iCloudFetchRecord(recordName: contactId, databaseScope: CKDatabaseScope.private, customZone: true, completion: { (contactRecord, error) in
                    if let ckerror = error as? CKError {
                        self.aErrorHandler.handleCkError(ckerror: ckerror)
                         self.navigationController!.popViewController(animated: true)
                    }
                    DispatchQueue.main.async {
                        if let record = contactRecord {
                            record.setObject("true" as NSString, forKey:"assignedEEP")
                        }
                    }
                }
                 self.navigationController!.popViewController(animated: true)
            }
        }

    })

}

Answer 1

每当我进入像这样的嵌套回调时，我都会尝试合并处理对代码中单个点的响应。在这种情况下，编码器的流行座右铭是：“不要重复自己”。

这里有一个建议，通过使您的主要功能有一个闭包，将错误处理和弹出合并到一个地方：

func iCloudSaveMeter(finished: @escaping (_ success: Bool, _ error: CKError?) -> Void){

  self.clOps.iCloudFetchRecord(recordName: locId, databaseScope: CKDatabaseScope.private, customZone: true, completion: { (locationRecord, error) in
    if error != nil {
      //:::
      finished(false, error)
    }
    self.iCloudFetchMeter(withLocationCKRecord: locationRecord!) { records, error in
      if error != nil {
        //:::
        finished(false, error)
      }
      if let _ = records?.first {
        self.clOps.iCloudFetchRecord(recordName: contactId, databaseScope: CKDatabaseScope.private, customZone: true, completion: { contactRecord, error in
          //:::
          finished(false, error)

          DispatchQueue.main.async {
            if let record = contactRecord {
              record.setObject("true" as NSString, forKey:"assignedEEP")
            }
          }
        }
      }

      //:::
      finished(true, nil)
    }
  })
}

//----
//Call it like this
iCloudSaveMeter(){ success, error in 
  //Pop
  if !success{ 
    self.navigationController!.popViewController(animated: true)
  }

  //Hande error
  if let error = error{
    self.aErrorHandler.handleCkError(ckerror: error)
  }
}