Swift - 从 NSViewController 捕获 keydown

Question

我想在我的小应用中捕捉关键事件。

我做了什么：

class ViewController : NSViewController {
...
  override func keyDown(theEvent: NSEvent) {
        if theEvent.keyCode == 124 {
            println("abc")
        } else {
            println("abcd")
        }
    }

    override var acceptsFirstResponder: Bool {
        return true
    }

    override func becomeFirstResponder() -> Bool {
        return true
    }

    override func resignFirstResponder() -> Bool {
        return true
    }

...
}

会发生什么：

按下某个键时，会播放Funk 音效。

我看到很多帖子都在谈论这是一个代表 NSView 和 NSViewController 没有访问权限的代表。但是keydown 函数override auto 在NSViewController 类型的类中完成，这让我相信这是错误的。

Answer 1

Xcode 8.2.1 • Swift 3.0.2

import Cocoa

class ViewController: NSViewController {

    @IBOutlet var textField: NSTextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        NSEvent.addLocalMonitorForEvents(matching: .flagsChanged) {
            self.flagsChanged(with: $0)
            return $0
        }
        NSEvent.addLocalMonitorForEvents(matching: .keyDown) {
            self.keyDown(with: $0)
            return $0
        }
    }
    override func keyDown(with event: NSEvent) {
        switch event.modifierFlags.intersection(.deviceIndependentFlagsMask) {
        case [.command] where event.characters == "l",
             [.command, .shift] where event.characters == "l":
            print("command-l or command-shift-l")
        default:
            break
        }
        textField.stringValue = "key = " + (event.charactersIgnoringModifiers
            ?? "")
        textField.stringValue += "\ncharacter = " + (event.characters ?? "")
    }
    override func flagsChanged(with event: NSEvent) {
        switch event.modifierFlags.intersection(.deviceIndependentFlagsMask) {
        case [.shift]:
            print("shift key is pressed")
        case [.control]:
            print("control key is pressed")
        case [.option] :
            print("option key is pressed")
        case [.command]:
            print("Command key is pressed")
        case [.control, .shift]:
            print("control-shift keys are pressed")
        case [.option, .shift]:
            print("option-shift keys are pressed")
        case [.command, .shift]:
            print("command-shift keys are pressed")
        case [.control, .option]:
            print("control-option keys are pressed")
        case [.control, .command]:
            print("control-command keys are pressed")
        case [.option, .command]:
            print("option-command keys are pressed")
        case [.shift, .control, .option]:
            print("shift-control-option keys are pressed")
        case [.shift, .control, .command]:
            print("shift-control-command keys are pressed")
        case [.control, .option, .command]:
            print("control-option-command keys are pressed")
        case [.shift, .command, .option]:
            print("shift-command-option keys are pressed")
        case [.shift, .control, .option, .command]:
            print("shift-control-option-command keys are pressed")
        default:
            print("no modifier keys are pressed")
        }
    }
}

---

要消除按下字符键时发出的咕噜声，您需要对视图进行子类化，重写方法 performKeyEquivalent 并返回 true。

import Cocoa

class View: NSView {
    override func performKeyEquivalent(with event: NSEvent) -> Bool {
        return true
    }
}

Sample Project

Answer 2

Swift4

刚刚为同样的问题找到了解决方案，Swift4。这背后的想法：如果按下的键是由自定义逻辑处理的，则处理程序应返回 nil，否则（未处理的）事件...

class MyViewController: NSViewController {
   override func viewDidLoad() {
      super.viewDidLoad()
      // ...
      NSEvent.addLocalMonitorForEvents(matching: .keyDown) {
         if self.myKeyDown(with: $0) {
            return nil
         } else {
            return $0
         }
      }
   }
   func myKeyDown(with event: NSEvent) -> Bool {
      // handle keyDown only if current window has focus, i.e. is keyWindow
      guard let locWindow = self.view.window,
         NSApplication.shared.keyWindow === locWindow else { return false }
      switch Int( event.keyCode) {
      case kVK_Escape:
         // do what you want to do at "Escape"
         return true
      default: 
         return false
      }
   }
}

我们在这里：按下键时没有 Purr / Funk 声音......

[更新] 增加了对 keyWindow 的检查。没有这个，即使另一个视图/窗口包含第一响应者，也会触发 keyDown()...

Answer 3

我试图找到 swift 3 的答案，这对我有用：

斯威夫特 3

import Cocoa

// We subclass an NSView

class MainView: NSView {

    // Allow view to receive keypress (remove the purr sound)
    override var acceptsFirstResponder : Bool {
        return true
    }

    // Override the NSView keydown func to read keycode of pressed key
    override func keyDown(with theEvent: NSEvent) {
        Swift.print(theEvent.keyCode)
    }

}

Answer 4

我设法从 NSWindowController 的子类中让它工作

class MyWindowController: NSWindowController {

    override func keyDown(theEvent: NSEvent) {
        print("keyCode is \(theEvent.keyCode)")
    }
}

更新：

import Cocoa

protocol WindowControllerDelegate {
    func keyDown(aEvent: NSEvent)
}

class WindowController: NSWindowController {

    var delegate: WindowControllerDelegate?

    override func windowDidLoad() {
        super.windowDidLoad()
        delegate = window?.contentViewController as! ViewController
    }
    override func keyDown(theEvent: NSEvent) {
        delegate?.keyDown(theEvent)
    }

}

和视图控制器：

class ViewController: NSViewController, WindowControllerDelegate {

    @IBOutlet weak var textField: NSTextField!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override var representedObject: AnyObject? {
        didSet {
        // Update the view, if already loaded.
        }
    }
    override func keyDown(theEvent: NSEvent) {
        textField.stringValue = "key = " + (theEvent.charactersIgnoringModifiers
            ?? "")
        textField.stringValue += "\ncharacter = " + (theEvent.characters ?? "")
        textField.stringValue += "\nmodifier = " + theEvent.modifierFlags.rawValue.description
    }

}