ios - 解析数据后如何循环API调用Swift

Question

我目前正在调用一个 API 来返回一堆 JSON 数据，对其进行解析，然后根据几个不同的标准对其进行排序。解析 JSON 数据后(它拉回一堆食谱)，它会通过一些函数进行过滤，这些函数会修剪结果池以更准确地满足用户的要求(即用户只需要准备时间少于 30 分钟的食谱) ) 。

有时在所有这些过滤器之后就没有更多的食谱了! - 当发生这种情况时，我喜欢自动重新调用 API。我不太确定如何在不创建某种无限循环的情况下执行此操作 - 下面的代码:

    SLApiCall.sharedCall.callGetApi(SearchUrl, params: dictPara) { (response, err ) -> () in

        var data = response!.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
        var localError: NSError?
        var jsonobj: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers, error: &localError) as? NSDictionary

        var arrTemp : NSArray = (jsonobj?.valueForKey("matches") as? NSArray)!

        var totalMatches = jsonobj.valueForKey("totalMatchCount") as! Int
        User.currentUser.setTotalRecipesMatched(totalMatches)
        let (max, min) = User.currentUser.ingredientsCountBasedOnLazyOption()

        printTimeElapsedWhenRunningCode("test12345") {

            self.arrRecipes = self.SortingArray(arrTemp.arrayByReplacingNullsWithBlanks(), maxLimit: max, minLimit: min)
        // This is where all the sorting happens, if this returns an empty array I want to re-call the method. 

        }

        User.currentUser.setList(self.arrRecipes!, param: theJSONText as! String)

        self.assignDemoData()

    }

Answer 1

您的问题的一个可能解决方案是使用 repeat-while 使用信号量来等待异步调用。请注意，尝试在主线程中执行此操作可能会阻塞您的 UI，因此可能希望它在辅助线程/队列中执行。还必须在主线程中更新 UI 等:

repeat{

  dispatch_semaphore_t sem = dispatch_semaphore_create(0);

  var gotData  = false

  SLApiCall.sharedCall.callGetApi(SearchUrl, params: dictPara) { (response, err ) -> () in

    var data = response!.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
    var localError: NSError?
    var jsonobj: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers, error: &localError) as? NSDictionary

    var arrTemp : NSArray = (jsonobj?.valueForKey("matches") as? NSArray)!

    var totalMatches = jsonobj.valueForKey("totalMatchCount") as! Int
    User.currentUser.setTotalRecipesMatched(totalMatches)
    let (max, min) = User.currentUser.ingredientsCountBasedOnLazyOption()

    printTimeElapsedWhenRunningCode("test12345") {

      self.arrRecipes = self.SortingArray(arrTemp.arrayByReplacingNullsWithBlanks(), maxLimit: max, minLimit: min)
      // This is where all the sorting happens, if this returns an empty array I want to re-call the method.
      if(self.arrRecipea.count){
        gotData = true

      }

    }

    User.currentUser.setList(self.arrRecipes!, param: theJSONText as! String)

    self.assignDemoData()
dispatch_semaphore_signal(sem)
  }

  //Wait until the block is called
  dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER); //Note- have a meaningful timeout here

}while (gotData != true)