Question

我已经在我的NewsController类中指定了一个segue到FullNews Class，它在我添加prepareforsegue函数之前就已经工作了。添加后，只要第一行的线程断点发生prepareforsegue，segue就不再发生冻结。这是两个班级。代码在

之下

import UIKit

class NewController: UIViewController, UITableViewDataSource, UITableViewDelegate, NSXMLParserDelegate {
    var parser: NSXMLParser = NSXMLParser()
    var info: [newsarticle] = []
    var postTitle: String = String()
    var postDesc: String = String()
    var eName: String = String()
    var index: Int = Int()
    /*
     // Only override drawRect: if you perform custom drawing.
     // An empty implementation adversely affects performance during animation.
     override func drawRect(rect: CGRect) {
     // Drawing code
     }
     */
   override func viewDidLoad() {
        let url:NSURL = NSURL(string: "http://brrsd.k12.nj.us/rss/News.xml")!
        parser = NSXMLParser(contentsOfURL: url)!
        parser.delegate = self
        parser.parse()
    }
    func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI namespaceURI: String?, qualifiedName qualifiedName: String?, attributes attributeDict: [String : String])
    {
        eName = elementName
        if elementName == "item" {
            postTitle = String()
            postDesc = String()
        }
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        // #warning Incomplete implementation, return the number of sections
        return 1
    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        // #warning Incomplete implementation, return the number of rows
        return info.count
    }
    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell: UITableViewCell
        if let reusedCell = tableView.dequeueReusableCellWithIdentifier("Cell") {
            cell = reusedCell
        } else {
            cell = UITableViewCell(style: .Default, reuseIdentifier: "Cell")
        }

        let news: newsarticle = info[indexPath.row]
        if let label = cell.textLabel {
            label.text = news.title
        }
        return cell    }

    func parser(parser: NSXMLParser, foundCharacters string: String) {
        let data = string.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
        if (!data.isEmpty) {
            if eName == "title" {
                postTitle += data
            } else if eName == "description" {
                postDesc += data
            }
        }
    }

    func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
        if elementName == "item" {
            let newsart: newsarticle = newsarticle()
            newsart.title = postTitle
            newsart.description = postDesc
            info.append(newsart)
        }
    }
    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        index = indexPath.row
            performSegueWithIdentifier("NewsTransfer", sender:self)
    }
     override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
       let Destination: FullNews = segue.destinationViewController as! FullNews
        Destination.info = info[index]
    }




    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}


import UIKit

class FullNews: UIViewController {
    var info: newsarticle = newsarticle()
    @IBOutlet weak var NewsTitle: UITableViewCell!
    @IBOutlet weak var Desc: UITextView!
    override func viewDidLoad() {
        super.viewDidLoad()
       NewsTitle.textLabel?.text = info.title
       Desc.text = info.description
        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}

为什么会这样？

Answer 1

不确定应用流程的流程，但也许您可以在执行if之前使用if let和prepareForSegue检查segue

 override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
     if segue.identifier == "NewsTransfer" {

         // additionally, you can print something here to see if this step worked
         //print("segue.identifier is NewsTransfer")

         if let destination = segue.destinationViewController as! FullNews {

              //print("destination is FullNews")

              destination.info = info[index]
         }
     }
}

还要确保您的segue已正确连接并命名为

EDIT 好像你已经创建了一个断点，因此它在断点处停止了。拖动左侧的蓝色箭头将其删除，代码将继续运行。

PrepareforSegue第一行期间的断点错误

1 个答案: