Ios 在swift中跨不同视图控制器访问UI属性

在我的应用程序中，我有一个摘要页面，该页面将显示每个付款人的付款人摘要和收件人列表。也就是说，摘要页面的左侧将有一个列表，单击每个列表将在右侧（iPad）显示其详细信息。为了在iPhone版本中重复使用相同的代码，我将其作为单独的视图控制器。也就是说，我有一个基本的ViewController（SummaryViewController）。在此子视图中，我查看列表的ViewController（SummaryListViewController）和详细信息的ViewController（SummaryDetailViewController）。现在，当基本视图控制器SummaryViewController加载时，我将子视图列表和详图视图控制器，如下所示

//ListView是基本ViewController中的一个视图，我将列表ViewController子视图到该视图

let listViewController = SummaryListViewController(nibName:"SummaryListViewController", bundle: nil)
addChildViewController(listViewController)
listViewController.view.frame = CGRect(x: 0, y: 0, width: self.ListView.frame.size.width, height: self.ListView.frame.size.height)
ListView.addSubview(listViewController.view)
listViewController.didMove(toParentViewController: self)

let detailViewController = SummaryDetailViewController(nibName: (UIDevice.current.userInterfaceIdiom == .pad ? "SummaryDetailViewController" : "SummaryDetailViewController_iPhone"), bundle: nil)
addChildViewController(detailViewController)
DetailView.frame = CGRect(x: DetailView.frame.origin.x, y: DetailView.frame.origin.y, width: self.DetailView.frame.size.width, height: self.DetailView.frame.size.height)
DetailView.addSubview(detailViewController.view)
detailViewController.didMove(toParentViewController: self)

//DetailView是基本ViewController中的一个视图，我在其中子视图Detail ViewController

let listViewController = SummaryListViewController(nibName:"SummaryListViewController", bundle: nil)
addChildViewController(listViewController)
listViewController.view.frame = CGRect(x: 0, y: 0, width: self.ListView.frame.size.width, height: self.ListView.frame.size.height)
ListView.addSubview(listViewController.view)
listViewController.didMove(toParentViewController: self)

let detailViewController = SummaryDetailViewController(nibName: (UIDevice.current.userInterfaceIdiom == .pad ? "SummaryDetailViewController" : "SummaryDetailViewController_iPhone"), bundle: nil)
addChildViewController(detailViewController)
DetailView.frame = CGRect(x: DetailView.frame.origin.x, y: DetailView.frame.origin.y, width: self.DetailView.frame.size.width, height: self.DetailView.frame.size.height)
DetailView.addSubview(detailViewController.view)
detailViewController.didMove(toParentViewController: self)

现在，问题是，我必须从SummaryListViewController的tableView didSelectRow调用SummaryDetailViewController中的一个方法，该方法将根据我发送的数据更新UI元素

为了实现这一目标，我尝试了以下几点：

我尝试在NotificationCenter中使用addObserver。当我点击列表时，我添加了一个观察者。该观察者触发detailViewController中的方法，该方法将更新UI元素。但这并不总是奏效。当我进入摘要页面时，请返回，如果我再次进入摘要页面并执行相同操作，则即使在ViewDidInviser中删除了观察者，也会调用观察者两次。我还从一些网站了解到，NotificationCenter不应该用于这种情况

第二，我尝试使用协议。我想我应该在SummaryListViewController中编写一个协议

let listViewController = SummaryListViewController(nibName:"SummaryListViewController", bundle: nil)
addChildViewController(listViewController)
listViewController.view.frame = CGRect(x: 0, y: 0, width: self.ListView.frame.size.width, height: self.ListView.frame.size.height)
ListView.addSubview(listViewController.view)
listViewController.didMove(toParentViewController: self)

let detailViewController = SummaryDetailViewController(nibName: (UIDevice.current.userInterfaceIdiom == .pad ? "SummaryDetailViewController" : "SummaryDetailViewController_iPhone"), bundle: nil)
addChildViewController(detailViewController)
DetailView.frame = CGRect(x: DetailView.frame.origin.x, y: DetailView.frame.origin.y, width: self.DetailView.frame.size.width, height: self.DetailView.frame.size.height)
DetailView.addSubview(detailViewController.view)
detailViewController.didMove(toParentViewController: self)

现在在SummaryDetailViewController的ViewDidLoad中，我想将委托的引用发送到listViewController，以便listViewController可以调用setSummaryDetails方法

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

func sendDelegateReferenceToListPage()
{
    let summaryListObj = SummaryListView()
    //This is where the error occurs. It throws the error since i try to cast SummaryDetailViewController to parameter of type SummaryDetailProtocol of SummaryListViewController
    summaryListObj.delegateFromSummaryDetails(delegate: self as! SummaryDetailProtocol)
}

---

有谁能帮我摆脱这个困境吗？协议解决方案是最好的。你可以这样用

SummaryListViewController文件：

protocol SummaryDetailProtocol {
    func setSummaryDetails()
}

class SummaryListViewController: UIViewController
{
    var summaryDetailsDelegate : SummaryDetailProtocol?

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath)
    {
        self.summaryDetailsDelegate?.setSummaryDetails()//use here
    }
}

class SummaryDetailViewController: UIViewController,SummaryDetailProtocol
{
    internal func setSummaryDetails() {
        //return whatever you want
    }


}

SummaryDetailViewController文件：

protocol SummaryDetailProtocol {
    func setSummaryDetails()
}

class SummaryListViewController: UIViewController
{
    var summaryDetailsDelegate : SummaryDetailProtocol?

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath)
    {
        self.summaryDetailsDelegate?.setSummaryDetails()//use here
    }
}

class SummaryDetailViewController: UIViewController,SummaryDetailProtocol
{
    internal func setSummaryDetails() {
        //return whatever you want
    }


}

最后将SummaryListViewController委托设置为SummaryDetailViewController：

let detailViewController = SummaryDetailViewController(nibName: (UIDevice.current.userInterfaceIdiom == .pad ? "SummaryDetailViewController" : "SummaryDetailViewController_iPhone"), bundle: nil)
addChildViewController(detailViewController)
DetailView.frame = CGRect(x: DetailView.frame.origin.x, y: DetailView.frame.origin.y, width: self.DetailView.frame.size.width, height: self.DetailView.frame.size.height)
DetailView.addSubview(detailViewController.view)
detailViewController.didMove(toParentViewController: self)

let listViewController = SummaryListViewController(nibName:"SummaryListViewController", bundle: nil)
addChildViewController(listViewController)
listViewController.view.frame = CGRect(x: 0, y: 0, width: self.ListView.frame.size.width, height: self.ListView.frame.size.height)
ListView.addSubview(listViewController.view)
listViewController.didMove(toParentViewController: self)
listViewController.summaryDetailsDelegate = detailViewController // set delegate detail view controller