将完成处理程序添加到 presentViewControllerAsSheet(NSViewController)？

Question

我正在尝试为我的主窗口/视图控制器（我正在使用情节提要）呈现一个工作表配置视图 (AddSoundEffect)，当配置视图控制器被关闭时，获取在 AddSoundEffect 中输入的值查看并将其传递回主视图。我当前在主视图控制器中的代码：

presentViewControllerAsSheet(self.storyboard!.instantiateControllerWithIdentifier("AddSoundEffect") as! AddSoundViewController

在AddSoundViewController.swift 文件中，关闭它的代码是：

self.dismissViewController(self)

为了传递数据，我有一个与类无关的元组，用于保存数据。如何向presentViewControllerAsSheet 添加完成处理程序，以及（可选）是否有更好的方法在视图控制器之间传递数据？

设置：Xcode 6.4 版，OS X 10.10.4

Answer 1

Delegation 模式对您来说是最简单的方法。

// Replace this with your tuple or whatever data represents your sound effect
struct SoundEffect {}

protocol AddSoundViewControllerDelegate: class {
  func soundViewController(controller: AddSoundViewController, didAddSoundEffect: SoundEffect)
}

//
// Let's say this controller is a modal view controller for adding new sound effects
//
class AddSoundViewController: UIViewController {
  weak var delegate: AddSoundViewControllerDelegate?

  func done(sender: AnyObject) {
    // Dummy sound effect info, replace it with your own data
    let soundEffect = SoundEffect()

    //
    // Call it whenever you would like to inform presenting view controller
    // about added sound effect (in case of Done, Add, ... button tapped, do not call it
    // when user taps on Cancel to just dismiss AddSoundViewController)
    //
    self.delegate?.soundViewController(self, didAddSoundEffect: soundEffect)

    // Dismiss self
    self.dismissViewControllerAnimated(true, completion: {})
  }
}

//
// Let's say this controller is main view controller, which contains list of all sound effects,
// with button to add new sound effect via AddSoundViewController
//
class SoundEffectsViewController: UIViewController, AddSoundViewControllerDelegate {
  func presentAddSoundEffectController(sender: AnyObject) {
    if let addSoundController = self.storyboard?.instantiateViewControllerWithIdentifier("AddSoundEffect") as? AddSoundViewController {
      addSoundController.delegate = self
      self.presentViewController(addSoundController, animated: true, completion: {})
    }
  }

  func soundViewController(controller: AddSoundViewController, didAddSoundEffect: SoundEffect) {
    // This method is called only when new sound effect is added
  }
}

另一种方法是使用闭包：

// Replace this with your tuple or whatever data represents your sound effect
struct SoundEffect {}

//
// Let's say this controller is a modal view controller for adding new sound effects
//
class AddSoundViewController: UIViewController {
  var completionHandler: ((SoundEffect) -> ())?

  func done(sender: AnyObject) {
    // Dummy sound effect info, replace it with your own data
    let soundEffect = SoundEffect()

    //
    // Call it whenever you would like to inform presenting view controller
    // about added sound effect (in case of Done, Add, ... button tapped, do not call it
    // when user taps on Cancel to just dismiss AddSoundViewController)
    //
    self.completionHandler?(soundEffect)

    // Dismiss self
    self.dismissViewControllerAnimated(true, completion: {})
  }
}

//
// Let's say this controller is main view controller, which contains list of all sound effects,
// with button to add new sound effect via AddSoundViewController
//
class SoundEffectsViewController: UIViewController {
  func presentAddSoundEffectController(sender: AnyObject) {
    if let addSoundController = self.storyboard?.instantiateViewControllerWithIdentifier("AddSoundEffect") as? AddSoundViewController {
      addSoundController.completionHandler = { [weak self] (soundEffect) -> () in
        // Called when new sound effect is added
      }
      self.presentViewController(addSoundController, animated: true, completion: {})
    }
  }
}

或许多其他方式，如发送通知，......任何适合您的需求。但是在这种特定情况下，委托模式或闭包是最好的方法。

---

我错过了你的问题是关于NSViewController。此示例适用于 iOS，但同样的模式可以在 OS X 上使用而不会出现任何问题。

Answer 2

检测工作表打开或关闭的最简单方法是使用Sheet Notifications：

class ViewController: NSViewController, NSWindowDelegate {

    override func viewDidLoad(){
        NSApplication.sharedApplication().windows.first?.delegate = self
    }
    func windowDidEndSheet(notification: NSNotification) {

    }
    func windowWillBeginSheet(notification: NSNotification) {

    }
}