Question

我必须按顺序检查一系列操作。但是如果任何操作失败，我需要在队列中执行列出的操作之前调用其他操作。

for example:

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

在每次操作中，我传递一个有效期仅为2小时的密钥...... 假设密钥是在上午10点生成的，我将开始从服务器获取数据，并且需要15分钟才能完全获取所有数据。

但问题是我已经开始在上午11:59开始获取数据并且在获取信息密钥到期期间。所以我需要再发送一个请求来获取密钥，然后继续进行下一步操作。

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

我尝试过的代码：

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 ..}
}

此代码无法正常运作。

它在队列中添加操作如下：

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顺序如下。

 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

任何帮助将不胜感激。

Answer 1

通过添加同步调用而非异步来解决此问题。

NSOperationQueue，操作块在SWIFT中无法正常工作

1 个答案: