关闭时如何将数据从模态视图控制器传回

Question

我已按照此处的说明进行操作，但我仍然不确定这部分：

modalVC.delegate=self;
        self.presentViewController(modalVC, animated: true, completion: nil) 

我试过以编程方式实例化视图控制器，但仍然无济于事。

这是我关闭模态视图控制器时的代码：

@IBAction func dismissViewController(_ sender: UIBarButtonItem) {
        self.dismiss(animated: true) { 
            //
        }
    }

我正在使用情节提要与模态视图进行拼接。

这是我希望传输回父视图控制器的数据：

var typeState = "top"
 var categoryState = "casual"

这是两个字符串值。

编辑：

我尝试从模态视图控制器传递数据，如下所示：

@IBAction func dismissViewController(_ sender: UIBarButtonItem) {
        self.dismiss(animated: true, completion: nil)
        delegate?.sendValue(value: "success")
        if let presenter = presentingViewController as? OOTDListViewController {
            presenter.receivedValue = "test"
        }
    }

而在父视图控制器上，我是这样做的：

func sendValue(value: NSString) {
        receivedValue = value as String
    }
  @IBAction func printReceivedValue(_ sender: UIButton) {
        print(receivedValue)
    }

当我点击打印按钮时，我仍然无法收到任何值。

模态视图控制器：

protocol ModalViewControllerDelegate
{
    func sendData(typeState: String, categoryState: String)
}

var delegate:ModalViewControllerDelegate!

var typeState = "top"
var categoryState = "casual"
@IBAction func dismissViewController(_ sender: UIBarButtonItem) {
        self.dismiss(animated: true, completion: nil)
        delegate?.sendData(typeState: typeState as String, categoryState: categoryState as String)

    }

父视图控制器：

class parentViewController: UICollectionViewController, ModalViewControllerDelegate {

var typeState: String?
var categoryState: String?
func sendData(typeState: String, categoryState: String) {
        self.typeState = typeState as String
        self.categoryState = categoryState as String
    }
 @IBAction func printReceivedValue(_ sender: UIButton) {
     print(typeState)
 }

编辑：

这是我不使用委托方法的新代码：

模态视图控制器：

@IBAction func dismissViewController(_ sender: UIBarButtonItem) {
        self.dismiss(animated: true, completion: nil)
        if let presenter = presentingViewController as? OOTDListViewController {
            presenter.typeState = typeState
            presenter.categoryState = categoryState
        }
    }

OOTDListViewController：

@IBAction func presentModalView(_ sender: UIBarButtonItem) {
        let modalView = storyboard?.instantiateViewController(withIdentifier: "filterViewController") as! ModalViewController
        let navModalView: UINavigationController = UINavigationController(rootViewController: modalView)
        self.present(navModalView, animated: true, completion: nil)
    }
@IBAction func printValue(_ sender: UIButton) {
        print(typeState)
        print(categoryState)
    }

Answer 1

根据您要传递的数据，您可以在呈现视图控制器中创建一个属性，您可以在关闭模态视图控制器时设置该属性，这样您就可以省去委托。

例如，您有一个ContactsViewController ，持有一个var contacts: [Contact] = []属性。 当你想创建一个新的联系人时，你会呈现一个模态视图控制器，其中包含创建新Contact对象所需的不同值。 当您完成并想要关闭视图控制器时，您可以像在代码中一样调用该函数，但在ContactsViewController设置该属性。 它看起来像这样：

@IBAction func dismissViewController(_ sender: UIBarButtonItem) {
    if let presenter = presentingViewController as? ContactsViewController {
        presenter.contacts.append(newContact)
    }
    dismiss(animated: true, completion: nil)
}

编辑：

如果你不想使用委托，这是你如何去做：

在您的OOTDListViewController ：

var testValue: String = ""

@IBAction func printReceivedValue(_ sender: UIButton) {
    print(testValue)
}

在您的模态视图控制器中（我将其称为PresentedViewController ）：

@IBAction func dismissViewController(_ sender: UIBarButtonItem) {
    // if your OOTDListViewController is part of a UINavigationController stack, this check will probably fail. 
    // you need to put a breakpoint here and check if the presentingViewController is actually a UINavigationController.
    // in that case, you will need to access the viewControllers variable and find your OOTDListViewController
    if let presenter = presentingViewController as? OOTDListViewController {
        presenter.testValue = "Test"
    }
    dismiss(animated: true, completion: nil)
}

如果你想使用委托，这是如何做到的：

在您的 OOTDListViewController 中：

protocol ModalDelegate {
func changeValue(value: String)
}

class OOTDListViewController: ModalDelegate {

var testValue: String = ""
@IBAction func presentViewController() {
    // here, you either create a new instance of the ViewController by initializing it, or you instantiate it using a storyboard. 
    // for simplicity, I'll use the first way
    // in any case, you cannot use a storyboard segue directly, bevause you need access to the reference of the presentedViewController object
    let presentedVC = PresentedViewController() 
    presentedVC.delegate = self
    present(presentedVC, animated: true, completion: nil)
}

func changeValue(value: String) {
     testValue = value
     print(testValue)
}

}

在您的PresentedViewController ：

class PresentedViewController {
    var delegate: ModalDelegate? 
    var testValue: String = ""

    @IBAction func dismissViewController(_ sender: UIBarButtonItem) {
       if let delegate = self.delegate {
            delegate.changeValue(testValue)
        }
        dismiss(animated: true, completion: nil)
    }

}

Answer 2

如果使用导航控制器，您必须首先获取 UINavigation 控制器，然后从导航控制器堆栈中获取正确的 ViewController。

这是我的代码在这种情况下的样子。

@IBAction func dismissViewController(_ sender: UIBarButtonItem) {
    if let navController = presentingViewController as? UINavigationController {
       let presenter = navController.topViewController as! OOTDListViewController
        presenter.testValue = "Test"
    }
    dismiss(animated: true, completion: nil)
}

Answer 3

你需要在dismissViewController方法中调用delegate方法

@IBAction func dismissViewController(_ sender: UIBarButtonItem) {
        delegate?.sendData(typeState: "top", categoryState: "casual")
        self.dismiss(animated: true) { 
            //
        }
 }

在你的 Modal ViewController 类中创建委托

var delegate: MyProtocol?

在 MyProtocol 和您正在分配委托的 PresentingViewController 中创建一个方法名称为 sendData 的协议，实现 MyProtocol 方法

protocol MyProtocol: class {
    func sendData(typeState: String, categoryState: String)
}

class ViewController: UIViewController, MyProtocol {
    var typeState: String?
    var categoryState: String?

    func sendData(typeState: String, categoryState: String) {
       self.typeState = typeState
       self.categoryState = categoryState
    }
 }

Answer 4

我正在使用标签栏，因此工作代码如下

            if let tabBar = self.presentingViewController as? UITabBarController {
            let homeNavigationViewController = tabBar.viewControllers![0] as? UINavigationController
            let homeViewController = homeNavigationViewController?.topViewController as! HomeController
            homeViewController._transferedLocationID = self.editingLocationID!
        }