Swift NSURL给有效的URL错误

Question

看这段代码：

let url = NSURL(string: physicst.image as String)
        if let url = url {
            let request = NSMutableURLRequest(URL: url)
            let task = session.dataTaskWithRequest(request, completionHandler: {(data, response, error) in
                if let data = data {
                    cell.imageView?.image = UIImage(data: data)
                }
            })
            task.resume()
        }else {
            print ("nill URL \(physicst.image)")
        }

所以我有一个字符串，而该字符串是一个url，我想加载它。

该代码位于表视图单元格中，因此每个单元格都将调用它。

如您所见，我正在检查url是否为nil，否则，我正在print声明。 几乎所有网址都不是nil，以下网址除外（完全有效）

http://commons.wikimedia.org/wiki/Special:FilePath/Kai_Manne_Börje_Siegbahn.jpg?width=300

http://commons.wikimedia.org/wiki/Special:FilePath/Виталий_Лазаревич_Гинзбург.jpg?width=300

http://commons.wikimedia.org/wiki/Special:FilePath/赤崎记念研究馆.jpg？width = 300

http://commons.wikimedia.org/wiki/Special:FilePath/Kai_Manne_Börje_Siegbahn.jpg?width=300

http://commons.wikimedia.org/wiki/Special:FilePath/赤崎记念研究馆.jpg？width = 300

您可能要争论的第一件事是对URL进行编码，这就是我这样做的方式：

var image = oneBinding["p"]!!["value"] as! NSString
                        image = image.stringByAddingPercentEncodingWithAllowedCharacters(.URLHostAllowedCharacterSet())!

但是即使是有效的网址也停止了工作。 我想念什么？

更新资料

这是我的UITableViewController的整个代码（很简单）

class PhysicistTableViewController: UITableViewController {

    var physicsts : [Physicst]?

    @IBOutlet var physicstsTableView: UITableView!



    override func viewDidLoad() {
        super.viewDidLoad()
        loadDataFromDBPedia()
    }

    func loadDataFromDBPedia()  {
        let session = NSURLSession.sharedSession()
        var url = "http://dbpedia.org/sparql/"
        let query = "http://dbpedia.org&query=select * {?o  dbo:thumbnail ?p . ?o dbo:award dbr:Nobel_Prize_in_Physics}"
        url = url + "?default-graph-uri=" + query.stringByAddingPercentEncodingWithAllowedCharacters(.URLHostAllowedCharacterSet())!
        url = url + "&format=JSON&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on"
        let request = NSMutableURLRequest(URL: NSURL(string: url)!)
        let task = session.dataTaskWithRequest(request, completionHandler: {(data, response ,error) in
            if let error = error {
                print ("\(error)")
            }
            if let response = response {
                let httpResponse = response as! NSHTTPURLResponse
                let statusCode = httpResponse.statusCode
                print("Status code = \(statusCode)")
            }
            if let data = data  {
                do {
                    let jsonResponse = try NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions())
                    let binding = jsonResponse["results"]!!["bindings"] as! NSArray
                    for oneBinding in binding {
                        let name = oneBinding["o"]!!["value"] as! NSString
                        let image = oneBinding["p"]!!["value"] as! NSString
                        //image = image.stringByAddingPercentEncodingWithAllowedCharacters(.URLHostAllowedCharacterSet())!
                        let physicst = Physicst(image: image, name: name)
                        if self.physicsts == nil {
                            self.physicsts = [Physicst]()
                        }
                        self.physicsts!.append(physicst)
                    }
                    self.physicstsTableView.reloadData()
                }catch _ {
                    print ("not well json-formatted response")
                }
            }
        })
        task.resume()
    }

    override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if self.physicsts == nil {
            return 0
        }else {
            return self.physicsts!.count
        }
    }


    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("physicstCell")! as UITableViewCell
        let row = indexPath.row
        let physicst = self.physicsts![row]
        cell.textLabel?.text = physicst.name as String
        if (physicst.imageData == nil) {
            let session = NSURLSession.sharedSession()
            let url = NSURL(string: physicst.image as String)
            if let url = url {
                let request = NSMutableURLRequest(URL: url)
                let task = session.dataTaskWithRequest(request, completionHandler: {(data, response, error) in
                    if let data = data {
                        let imageData = UIImage(data: data)
                        cell.imageView?.image = imageData
                        physicst.imageData = imageData
                        self.physicstsTableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.None)
                    }
                })
                task.resume()
            }else {
                print ("nill URL \(physicst.image)")
            }
        }else {
            cell.imageView?.image = physicst.imageData!
        }
        return cell
    }
}

Answer 1

您应该使用的方法是

stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLQueryAllowedCharacterSet())

从操场上拍摄：

NSURL(string:"http://commons.wikimedia.org/wiki/Special:FilePath/Kai_Manne_Börje_Siegbahn.jpg?width=300".stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLQueryAllowedCharacterSet())!)

给出结果

http://commons.wikimedia.org/wiki/Special:FilePath/Kai_Manne_B%C3%B6rje_Siegbahn.jpg?width=300

这是有效的:)

适应您的代码，它提供了：

let url = NSURL(string: (physicst.image as String).stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLQueryAllowedCharacterSet()!)

当心被迫打开包装！

Answer 2

URLHostAllowedCharacterSet仅包含此"#%/<>?@\\^ {|}

并且您的URL字符串包含: ..因此为此进行自定义设置

 let yourString = "http://commons.wikimedia.org/wiki/Special:FilePath/Kai_Manne_Börje_Siegbahn.jpg?width=300"
 let customSet =  NSCharacterSet(charactersInString:"=\"#%/:<>?@\\^`{|}").invertedSet
 let finalString = yourString.stringByAddingPercentEncodingWithAllowedCharacters(customSet)   

有关更多信息。 检查这个答案