Question

有谁知道如何解决这个问题？

问题是prepareForSegue函数没有获得chanceRain变量。由于某种原因chanceRain只在任务变量中有一个值。有人知道如何解决这个问题吗？我试图在游乐场修复它但我不能在其中导入SWXMLHash。

import UIKit
import SWXMLHash

class ViewController: UIViewController, UITableViewDelegate {

    var cellContent = [""]
    var indexOfTime = 0
    var chanceRain = ""
    var defaults = NSUserDefaults(suiteName: "group.com.royvano.paraplu")
    var rainInt :Int = 0



    @IBOutlet var cityInput: UITextField!

    func enumerate(indexer: XMLIndexer) {
        for child in indexer.children {
            NSLog(child.element!.name)
            enumerate(child)
        }
    }


    @IBAction func button(sender: AnyObject) {

        var url = NSURL(string: "http://api.worldweatheronline.com/free/v2/weather.ashx?key=ca89103dfe0a8b844a0a1e1249820&q=" +
            cityInput.text.stringByReplacingOccurrencesOfString(" ", withString: "-") + "/" + cityInput.text.stringByReplacingOccurrencesOfString(" ", withString: "-") + "/" + "&num_of_days=2&tp=3&format=xml")

        let task = NSURLSession.sharedSession().dataTaskWithURL(url!, completionHandler: { (data, response, error) -> Void in

            var urlContent = NSString(data: data, encoding: NSUTF8StringEncoding)

            println(url)

            var xml = SWXMLHash.parse(urlContent!)

            for elem in xml["data"]["weather"][0]["hourly"][self.indexOfTime]{

                self.chanceRain = (elem["chanceofrain"].element!.text!)

                self.defaults?.setObject(self.chanceRain, forKey: "rainPercentage")

                self.defaults?.synchronize()


                 self.performSegueWithIdentifier("btnSubmitSegue", sender: self)

            }

            println(self.chanceRain)

        })
        task.resume()

    }

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {



        if(segue.identifier == "btnSubmitSegue"){

            var svc: viewTwo = segue.destinationViewController as viewTwo

            svc.datapassed = "There is " + self.chanceRain + "% chance of rain" //dit werkt, maar chanceRain niet..?


        } }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        cellContent = ["01:00","04:00","07:00", "10:00", "13:00", "16:00", "19:00", "22:00"]
    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        return cellContent.count
    }

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

        let cell = UITableViewCell(style: UITableViewCellStyle.Default  , reuseIdentifier: "Cell")

        cell.textLabel?.text = "\(cellContent[indexPath.row])"

        return cell }

    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath){

        indexOfTime = indexPath.row



    }



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



}

此处的viewTwo类：

import Foundation
import UIKit

class viewTwo: UIViewController {

    @IBOutlet var label: UILabel!

    var datapassed:String! = ""

    override func viewDidLoad() {

        label.text = datapassed }

}

Answer 1

由于除了IBAction button(_:)之外，您在按下按钮时触发了segue，因此当发生segue时，chanceOfRain变量不会被更新。这是因为chanceOfRain在异步调用的块中更新，这意味着需要时间来更新。到更新时，prepareForSegue可能已经解决。

要解决此问题，请不要在故事板中按下按钮上的segue。相反，使它成为从第一个ViewController到第二个具有标识符的ViewController的常规segue。然后，在知道performSegueWithIdentifier(_:sender:)已更新后，您可以在异步调用的块中调用chanceOfRain。这将确保数据正确传递。

无法变量正确

1 个答案: