我无法从委托swift加载数据

Question

我正在使用委托将通过JSON收集的数据传递给几个UIViewControllers 。

我的设置是这样的

我以编程方式在MainViewController内为ContainedViewController创建了容器：

 func createContainer(){
      let controller: UIViewController = (storyboard?.instantiateViewControllerWithIdentifier("containedVC"))! as UIViewController
      controller.view.frame = CGRect(x: 20, y: self.view.frame.height-220, width: self.view.frame.width-40, height: 200)
      view.addSubview(controller.view)
      self.addChildViewController(controller)
}

我在另一个类上使用JSON收集了一些数据（ 然后将它们首先传递到MainViewController上 ）并将它们传递给MainViewController之后，调用了该函数。 我用于此目的的代码是：

func setForecast(forecast: Forecast) {
    self.delegateForecast?.loadOnContained(forecast)
    print("did forecast pass to delegate?")
    createContainer()
}

我还在MainViewController上设置了一个协议 ：

protocol dataForContainedDelegate{
    func loadOnContained(forecast: Forecast)
}

和一个变量 ：

var delegateForecast: dataForContainedDelegate?

我的containedVC代码是：

import UIKit

class ContainedViewController: UIViewController, UIPageViewControllerDataSource, dataForContainedDelegate {

    var forecastService = MainViewController()

    var pageViewController: UIPageViewController!
    var pageDates: NSArray!
    var pageHighTemps: NSArray!
    var pageLowTemps: NSArray!
    var pageDescriptions: NSArray!
    //var pageImages: NSArray!

    func loadOnContained(forecast: Forecast) {
        print("forecast loaded")
        self.pageDates = forecast.dates
        print("dates set")
        self.pageHighTemps = forecast.highTemps
        self.pageLowTemps = forecast.lowTemps
        self.pageDescriptions = forecast.descriptionsArray
        createVCs()
    }
    func createVCs(){
        self.pageViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController") as! UIPageViewController
        self.pageViewController.dataSource = self
        let startVC = self.viewControllerAtIndex(0) as ContentViewController
        let viewControllers = NSArray(object: startVC)

        self.pageViewController.setViewControllers(viewControllers as? [UIViewController], direction: .Forward, animated: true, completion: nil)
        self.pageViewController.view.frame = CGRectMake(0, 0, self.view.frame.width, self.view.frame.height)

        self.addChildViewController(self.pageViewController)
        self.view.addSubview(self.pageViewController.view)
        self.pageViewController.didMoveToParentViewController(self)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        self.forecastService.delegateForecast = self
        print("contained load")
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func viewControllerAtIndex(index: Int) -> ContentViewController{

        if(self.pageDates.count == 0) || (index >= self.pageDates.count){  //MARK2: ---ERRON IN THIS LINE "fatal error: unexpectedly found nil while unwrapping an Optional value (lldb)
            return ContentViewController()
        }

        let vc: ContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("ContentViewController") as! ContentViewController

        vc.pageIndex = index
        vc.dateText = self.pageDates[index] as! String
        vc.highTmp = self.pageHighTemps[index] as! String
        vc.lowTmp = self.pageLowTemps[index] as! String
        vc.descText = self.pageDescriptions[index] as! String
        //vc.weatherFile = self.pageImages[index] as! String

        return vc
    }
    func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
        let vc = viewController as! ContentViewController
        var index = vc.pageIndex as Int
        if (index == 0 || index == NSNotFound){
            return nil
        }
        index--
        return self.viewControllerAtIndex(index)
    }

    func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {

        let vc = viewController as! ContentViewController
        var index = vc.pageIndex as Int
        if (index == NSNotFound){
            return nil
        }
        index++
        if (index == self.pageDates.count){
            return nil
        }
        return self.viewControllerAtIndex(index)
    }

    func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
        return self.pageDates.count
    }

    func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
        return 0
    }
}

当我运行应用程序时，出现此屏幕

在我的输出窗口中，没有关于“预加载”或“日期设置”的任何信息，但是有“包含的负载”（在viewDidLoad函数下）：

self.weatherService.delegate = self **** at main
from DefaultsSet: Los Angeles
Weather Service class city: Los Angeles
Date: 21 Feb 2016 , High: 20.6 °C , Low: 10.0 °C, Text: Clear
Date: 22 Feb 2016 , High: 28.3 °C , Low: 12.8 °C, Text: Sunny
Date: 23 Feb 2016 , High: 27.8 °C , Low: 12.2 °C, Text: Partly Cloudy
Set Weather main view
did forecast pass to delegate?
contained load

---

混乱背后的原因

我想要当用户按下Set City按钮时能够选择一个城市，然后从JSON数据解析到MainViewController （ 当前条件 ）和containedVC的PageViewController （ 接下来几天的Forecast ）中的PageViewController上。

所以我的想法是

1. 用户设置城市
2. 调用WeatherService并将所有数据传递到MainViewController
3. 在MainViewController setWeather函数上，我们在MainViewController设置标签
4. 在setForecast上FUNC MainViewController我们传递数据给containedVC和动态创建页面。

但是似乎数据永远不会到达containedVC 。 有什么原因吗？

此外，如果我将其设置为WeatherServiceDelegate并在viewDidLoad上调用setWeather(city: String)则可以将数据加载到containedVC ，但是这样，我必须再次设置城市，并且不能在按下Set City按钮时自动加载数据。

Answer 1

调用委托的时间，实际上没有设置委托（即委托为nil）。

据我了解，您只需要将数据从父viewController传递给子对象，就可以通过变量而不是使用委托将数据传递给子对象，如下所示，

func createContainer(){
  let controller: UIViewController = (storyboard?.instantiateViewControllerWithIdentifier("containedVC"))! as UIViewController
  controller.data = forecast // like this
  controller.view.frame = CGRect(x: 20, y: self.view.frame.height-220, width: self.view.frame.width-40, height: 200)
  view.addSubview(controller.view)
  self.addChildViewController(controller)

}