帶操作塊的NSOperationQueue在SWIFT中無法按預期工作

Question

我必須按順序檢查一系列操作。 但是如果任何操作失敗，我需要在執行隊列中列出的操作之前調用其他操作。

for example:

priority 1 : Fetch all companies lookups
priority 2 : Fetch all regions
priority 3...N : Fetch all cities individually for each region

在每個操作中，我傳遞一個僅在2小時內有效的密鑰...假設密鑰是在上午10點生成的，我將開始從服務器獲取數據，並且需要15分鍾才能完全獲取所有數據。

但問題是我已在上午11:59開始獲取數據，並且在獲取信息密鑰期間已過期。 因此，我需要再發送一個請求以獲取密鑰，並進一步進行下一步操作。

so it looks like:
priority 1 : Fetch all companies lookups with key
priority 2 : Fetch all regions (i.e. 4 Regions available) with key
   priority 3 : Fetch all cities for region 1 with key
   priority 4 : Fetch all cities for region 2 with key (here key is expire) so for taking new key need to add new operation here, which fetch new key which is valid again for next two hours.
   priority 5 : Fetch all cities for region 3 with new key
   priority 6 : Fetch all cities for region 4 with new key

我嘗試過的代碼：

var queue = NSOperationQueue.mainQueue()
queue.addOperationWithBlock({
  callService(“http://dsn/FetchingCompanyData”)
}

queue.addOperationWithBlock({
  callService(“http://dsn/FetchingRegionData”)
  //get region List here
  for region in regions{
   queue.addOperationWithBlock({
    callService(“http://dsn/FetchingCities?region=\(region.code)”)
    //check in response if response return message like KEY_EXPIRE
    if(error){
      queue.addOperationWithBlock({
        var newKey = callService(“http://dsn/FetchingCities?region=\(region.code)”)
        setKeyToCache(newKey)
      })
    }
  }
}
}

fun callService(urlStr: String){
    let myURL = NSURL(string: urlStr)!
    var key = getKeyFromCache()
    var request = NSMutableURLRequest(URL: myURL)
    var errorHandling = ErrorHandling()
    request.HTTPMethod = "POST"
    request.timeoutInterval = 10000.0
    request.addValue("application/xml", forHTTPHeaderField: "Content-Type")
    request.addValue("application/xml", forHTTPHeaderField: "Accept")
    request.setValue("Basic \(key)", forHTTPHeaderField: "Authorization")

    NSURLConnection.sendAsynchronousRequest(request, queue: queue) { response, data, error in ..}
}

該代碼無法按需工作。

它在隊列中添加操作，如下所示：

Queue:
Operation 1: Fetch companies
Operation 2: Fetch Regions
Operation 3: Fetch cities for region 1
Operation 4: Fetch cities for region 2
Operation 5: Fetch cities for region 3
Operation 6: Fetch cities for region 4
Operation 7: Fetch new key for region 1
Operation 7: Fetch new key for region 2
Operation 7: Fetch new key for region 3
Operation 7: Fetch new key for region 4

而不是我想要的操作順序如下。

 Operation 1: Fetch companies
    Operation 2: Fetch Regions
    Operation 3: Fetch cities for region 1
    Operation 4: Fetch cities for region 2
    Operation 5: Fetch new key for region 2
    Operation 6: Again Fetch cities for region 2
    Operation 7: Fetch cities for region 3
    Operation 8: Fetch cities for region 4

任何幫助將不勝感激。

Answer 1

通過添加同步調用而不是異步解決了此問題。