swift - 返回完成处理程序后重新执行 while 循环

Question

我有一个 while 循环，如果返回的数字为 0，我希望继续执行。目前的问题是循环永远不会停止，因为它不等待完成处理程序返回其结果(这需要几秒钟) .如何在 if 语句完成后才重新执行 while 循环？

while 循环

var empty = true
    override func viewDidLoad() {
            repeat {
        str = iFunctions.generateRandomStringWithLengthOf(4) as String
                iFunctions.getServerData(str){(msg)
                    in
                    if (msg > 0){
                        self.empty = false
                        print("not empty")
                    }
                    else{
                        print("empty")
                    }
                    self.count = msg!
                    print(self.count)

                }
            } while(empty)
        }

函数

func getServerData(q: String, completionHandler: (Int?) -> ()) -> () {
        let params = [
            "term": q
        ]
        Alamofire.request(.GET, "URL", parameters: params)
            .responseJSON { response in
                if response.result.error == nil {
                    let json = JSON(response.result.value!)
                    //add data to struct
                    completionHandler(json["results"].count)
                }
        }

    }

Answer 1

你不应该用循环来做这件事。这就是 Alamofire 的全部意义所在，因此您不必处理线程和循环。您正在使用高级指令:回调。

其实很容易解决你的问题:

var empty = true
override func viewDidLoad() {
 self.tryGettingDataFromServer()
}

func tryGettingDataFromServer(){
 str = iFunctions.generateRandomStringWithLengthOf(4) as String
 iFunctions.getServerData(str){(msg) in
    if (msg > 0){
        self.empty = false
        print("not empty")
    }
    else{
        // The closure keeps a reference to self and calls
        // the tryGettingDataFromServer again if "empty"
        // It will happen infinitely until "not empty"
        self.tryGettingDataFromServer()
    }
    self.count = msg!
    print(self.count)
  }

}