Question

我有一个循环JSON数据并在tableview中显示的页面。我正确地得到了正确但当它在页面上显示时，它非常慢。我试图打印json以查看它检索json数据的速度有多快，而且非常快。还有一件很奇怪的事情就是当它加载时，如果我拖动页面，一切都会立即显示。下面是我在viewdidload函数中放入的代码

        self.PoTable.separatorStyle = UITableViewCellSeparatorStyle(rawValue: 0)!
        self.navigationController?.navigationBar.topItem?.backBarButtonItem = UIBarButtonItem(title: "", style: .Plain, target: nil, action: nil)
        PoTable.delegate = self
        PoTable.dataSource = self
        self.PoTable.addSubview(self.activityIndicatorView)
        UIApplication.sharedApplication().networkActivityIndicatorVisible = true
        activityIndicatorView.startAnimating()
        let url = NSURL(string: SharedClass().clsLink + "/json/POList.cfm")
        let session = NSURLSession.sharedSession()
        let task = session.dataTaskWithURL(url!, completionHandler: {data, response, error -> Void in
            if(error != nil) {
                // If there is an error in the web request, print it to the console
                println(error.localizedDescription)
            }
            var err: NSError?
            let res = response as! NSHTTPURLResponse!
            if(res != nil){
                if (res.statusCode >= 200 && res.statusCode < 300){
                    self.jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as! NSDictionary
                    if(err != nil) {
                        // If there is an error parsing JSON, print it to the console
                        println("JSON Error \(err!.localizedDescription)")
                    }
                    var resultsArr: NSArray = self.jsonResult["results"] as! NSArray
//                        println(resultsArr)
                    self.PoList = PoInfo.poInfoWithJSON(resultsArr)
                    self.PoTable!.reloadData()
                    self.activityIndicatorView.stopAnimating()
                    self.activityIndicatorView.hidden = true
                }
                else{
                    UIApplication.sharedApplication().networkActivityIndicatorVisible = false
                    SharedClass().serverAlert(self)
                }
            }else{
                UIApplication.sharedApplication().networkActivityIndicatorVisible = false
                self.activityIndicatorView.stopAnimating()
                SharedClass().serverAlert(self)
            }
        })
        task.resume()

请帮助

Answer 1

在if闭包中尝试此异步范围dispatch_async(dispatch_get_main_queue())，如

  dispatch_async(dispatch_get_main_queue()) {
             if (res.statusCode >= 200 && res.statusCode < 300){
                self.jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as! NSDictionary
                if(err != nil) {
                    // If there is an error parsing JSON, print it to the console
                    println("JSON Error \(err!.localizedDescription)")
                }
                var resultsArr: NSArray = self.jsonResult["results"] as! NSArray
                self.PoList = PoInfo.poInfoWithJSON(resultsArr)
                self.PoTable!.reloadData()
                self.activityIndicatorView.stopAnimating()
                self.activityIndicatorView.hidden = true
            }
  }

swift tableview显示json数据非常慢

1 个答案: