關閉時如何將數據從模態視圖控制器傳回

Question

我已按照此處的說明進行操作，但我仍然不確定這部分：

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

我試過以編程方式實例化視圖控制器，但仍然無濟於事。

這是我關閉模態視圖控制器時的代碼：

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

我正在使用情節提要與模態視圖進行拼接。

這是我希望傳輸回父視圖控制器的數據：

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

這是兩個字符串值。

編輯：

我嘗試從模態視圖控制器傳遞數據，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"
        }
    }

而在父視圖控制器上，我是這樣做的：

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

當我點擊打印按鈕時，我仍然無法收到任何值。

模態視圖控制器：

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)

    }

父視圖控制器：

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)
 }

編輯：

這是我不使用委托方法的新代碼：

模態視圖控制器：

@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

根據您要傳遞的數據，您可以在呈現視圖控制器中創建一個屬性，您可以在關閉模態視圖控制器時設置該屬性，這樣您就可以省去委托。

例如，您有一個ContactsViewController ，持有一個var contacts: [Contact] = []屬性。 當你想創建一個新的聯系人時，你會呈現一個模態視圖控制器，其中包含創建新Contact對象所需的不同值。 當您完成並想要關閉視圖控制器時，您可以像在代碼中一樣調用該函數，但在ContactsViewController設置該屬性。 它看起來像這樣：

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

編輯：

如果你不想使用委托，這是你如何去做：

在您的OOTDListViewController ：

var testValue: String = ""

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

在您的模態視圖控制器中（我將其稱為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，這是如何做到的：

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

如果使用導航控制器，您必須首先獲取 UINavigation 控制器，然后從導航控制器堆棧中獲取正確的 ViewController。

這是我的代碼在這種情況下的樣子。

@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方法中調用delegate方法

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

在你的 Modal ViewController 類中創建委托

var delegate: MyProtocol?

在 MyProtocol 和您正在分配委托的 PresentingViewController 中創建一個方法名稱為 sendData 的協議，實現 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

我正在使用標簽欄，因此工作代碼如下

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