Question

我试图创建一个接收URL的简单函数，只返回网页的HTML。 NSURLSessionDataTask本身似乎有用，我可以在println(data)时看到整个html。但是func只返回初始值＆＃34;＃！？＆＃34;。我怀疑DataTask是否异步？

我该如何处理？

    func loadHTML(targetURL: String) -> String {

    var theTargetURL = NSURL(string:targetURL)
    var theResult = "#!?"

    var request: NSURLRequest = NSURLRequest(URL:theTargetURL)
    let config = NSURLSessionConfiguration.defaultSessionConfiguration()
    let session = NSURLSession(configuration: config)

    let task : NSURLSessionDataTask = session.dataTaskWithRequest(request, completionHandler: {(data, response, error) in
        println(NSString(data: data, encoding: NSASCIIStringEncoding))

        if error != nil {
            println(error.localizedDescription)
            theResult = "error"
        }
        if data != nil {
            theResult = NSString(data: data, encoding: NSASCIIStringEncoding)
            println("RECEIVED\t\t\(countElements(theResult)) CHARS")
        }
    });
    task.resume()

    return theResult
}

Answer 1

以下是使用完成处理程序执行此操作的示例。

 typealias CompletionBlock = (NSData!, NSURLResponse!, NSError!) -> Void

  func loadHtml(targetUrlString: String, completion: CompletionBlock){

    let targetUrl = NSURL(string: targetUrlString)
    let request = NSURLRequest(URL: targetUrl)

    let session = NSURLSession.sharedSession()
    let task = session.dataTaskWithRequest(request, completionHandler: completion)
    task.resume()

  }

然后，从您需要的方法中调用它，

func viewDidLoad(){
  super.viewDidLoad()
  loadHtml("http://google.com", completion: { (responseData: NSData!, response: NSURLResponse!, error: NSError!) -> Void in

    if responseData != nil{

      let resultString = NSString(data: responseData, encoding: NSASCIIStringEncoding)
      println(resultString)

      /* 
        do some task or update on the main thread
        dispatch_async(dispatch_get_main_queue){
          myActivityIndicator.stopAnimating()
        }
      */

    }else if error != nil{

      println("Error occurred: \(error.localizedDescription)")

    }

  })

NSURLSessionDataTask：func接收但不返回任何数据

1 个答案: