Swift NSURLSession真的非常慢

Question

我NSURLSession在我的应用程序中使用如下:

func wsQAshowTag(tag: Int, completion: ([AnyObject]! -> Void)) {
        let requestString = NSString(format: “URL”, tag) as String
        let url: NSURL! = NSURL(string: requestString)
        let task = NSURLSession.sharedSession().dataTaskWithURL(url, completionHandler: {
            data, response, error in
            do {
                let result = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments) as! [AnyObject]
                completion(result)
            }
            catch {
                completion(nil)
            }
        })
        task.resume()
    }

这可以按预期工作,但我发现它非常慢,当我使用时NSURLConnection我发现它非常快(这是使用相同的URL)NSURLSession如果NSURLConnection非常快,怎么来非常慢？还有加速NSURLSession吗？

这是我如何称呼它:

self.wsQAshowTag(Int(barcode)!, completion: { wsQAshowTagArray in
     //Code Here
})

Answer 1

您需要将UI更新发送到主队列.如果更新它而不将其发送到主队列,则更新数据可能需要很长时间.

您还需要进行换行,completion(result)因为我们正在解析JSON.

代码抓取存储的完成处理程序并在主线程上调用它.

func wsQAshowTag(tag: Int, completion: ([AnyObject]! -> Void)) {
let requestString = NSString(format: "URL", tag) as String
let url: NSURL! = NSURL(string: requestString)
let task = NSURLSession.sharedSession().dataTaskWithURL(url, completionHandler: {
    data, response, error in
    do {
        let result = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments) as! [AnyObject]
        dispatch_async(dispatch_get_main_queue()) {
            completion(result)
        }
    } catch {
        dispatch_async(dispatch_get_main_queue()) {
        completion(nil)
        }
        print("error serializing JSON: \(error)")
    }
})
task.resume()
}