一系列 cloudkit 回调 - 何时弹出到上一个控制器

Question

我有一系列连续的云工具包调用来根据以前的提取来提取记录。这些提取中的任何一个都可能失败，然后我必须弹出到以前的控制器。由于有太多地方提取失败，我必须在许多位置将 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并只调用一次弹出窗口吗？

 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

每当我遇到这样的嵌套回调时，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，编码员的流行格言会有所帮助："don't repeat yourself"

这里有一个通过让你的主函数有一个闭包来合并错误处理和弹出到一个地方的建议：

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)
  }
}

一系列 cloudkit 回调 - 何时弹出到上一个控制器

series of cloudkit callbacks - when to popover to previous controller

swift

cloudkit