keyDown doesn't work swift

问题

That's my code:

override func keyDown(theEvent: NSEvent) {
    super.keyDown(theEvent)
    switch theEvent.character {
    case NSLeftArrowFunctionKey:
        println(1)
    case NSRightArrowFunctionKey:
        println(2)
    case NSDownArrowFunctionKey:
        println(3)
    case NSUpArrowFunctionKey:
        println(4)
    default:
        break
    }
}

As you can see, I try to recognize if one of arrow buttons was pressed, but it never works. Even the function keyDown never seems to be called.

That's what is written in viewDidAppear, if this can help you to provide the answer:

override func viewDidAppear() {
    super.viewDidAppear()
    self.view.window?.styleMask = NSClosableWindowMask | NSMiniaturizableWindowMask | NSTitledWindowMask
    var frame = self.view.window?.frame
    var newHeight = CGFloat(438)
    var newWidth = CGFloat(415)
    frame?.size = NSMakeSize(newWidth, newHeight)
    self.view.window?.setFrame(frame!, display: true)
    self.view.window?.backgroundColor = NSColor.darkGrayColor()
}

In viewDidLoad I just add some non-selectable and non-editable NSTextFields like that:

var x = CGFloat(0)
    var y = CGFloat(0)
    var tag = 1

    for var i = 0; i < 4; i++ {
        for var j = 0; j < 4; j++ {
            var tile = NSTextField(frame: NSRect(x: x, y: y, width: 100, height: 100))
            tile.enabled = false
            tile.stringValue = ""
            tile.font = NSFont(name: "Helvetica", size: 75)
            tile.backgroundColor = NSColor.lightGrayColor()
            tile.editable = false
            tile.selectable = false
            tile.drawsBackground = true
            tile.alignment = NSTextAlignment(rawValue: 2)!
            tile.tag = tag
            x += 105
            ar.append(tile)
            self.view.addSubview(tile)
            tag++
        }
        x = 0
        y += 105
    }

I just have no idea why keyDown doesn't work, so I'll really appreciate any help.

EDIT:

The whole class code:

import Cocoa
import AppKit
import Foundation

class _048Main: NSViewController {

var ar : Array<NSTextField> = []
var left = 0

var dict : Dictionary<Int, NSColor> = [:]

var pic2 = NSColor.redColor()
var pic4 = NSColor.whiteColor()
var pic8 = NSColor.orangeColor()
var pic16 = NSColor.magentaColor()
var pic32 = NSColor()
var pic64 = NSColor()
var pic128 = NSColor()
var pic256 = NSColor() // Some colors will be added
var pic512 = NSColor()
var pic1024 = NSColor()
var pic2048 = NSColor()


override func viewDidLoad() {
    super.viewDidLoad()

    dict[2] = pic2
    dict[4] = pic4
    dict[8] = pic8
    dict[16] = pic16
    dict[32] = pic32
    dict[64] = pic64
    dict[128] = pic128
    dict[256] = pic256
    dict[512] = pic512
    dict[1024] = pic1024
    dict[2048] = pic2048

    var x = CGFloat(0)
    var y = CGFloat(0)
    var tag = 1

    for var i = 0; i < 4; i++ {
        for var j = 0; j < 4; j++ {
            var tile = NSTextField(frame: NSRect(x: x, y: y, width: 100, height: 100))
            tile.enabled = false
            tile.stringValue = ""
            tile.font = NSFont(name: "Helvetica", size: 75)
            tile.backgroundColor = NSColor.lightGrayColor()
            tile.editable = false
            tile.selectable = false
            tile.drawsBackground = true
            tile.alignment = NSTextAlignment(rawValue: 2)!
            tile.tag = tag
            x += 105
            ar.append(tile)
            self.view.addSubview(tile)
            tag++
        }
        x = 0
        y += 105
    }
    left = 16
    generateTile()
    generateTile()
}

func generateTile() {
    var r = Int(arc4random_uniform(UInt32(left)))
    var tmp = 0
    for var i = 0; i < 16; i++ {
        if ar[i].stringValue == "" {
            if tmp == r {
                var t = Int(arc4random_uniform(10))
                switch t {
                case 0...1:
                    ar[i].stringValue = "2"
                    ar[i].backgroundColor = pic2
                default:
                    ar[i].stringValue = "4"
                    ar[i].backgroundColor = pic4
                }
                left--
                break
            }
            tmp++
        }
    }
}

override func viewDidAppear() {
    super.viewDidAppear()
    self.view.window?.styleMask = NSClosableWindowMask | NSMiniaturizableWindowMask | NSTitledWindowMask
    var frame = self.view.window?.frame
    var newHeight = CGFloat(438)
    var newWidth = CGFloat(415)
    frame?.size = NSMakeSize(newWidth, newHeight)
    self.view.window?.setFrame(frame!, display: true)
    self.view.window?.backgroundColor = NSColor.darkGrayColor()
}


override func keyDown(theEvent: NSEvent) {
    super.keyDown(theEvent)
    switch theEvent.character {
    case NSLeftArrowFunctionKey:
        println(1)
    case NSRightArrowFunctionKey:
        println(2)
    case NSDownArrowFunctionKey:
        println(3)
    case NSUpArrowFunctionKey:
        println(4)
    default:
        super.mouseDown(theEvent)
    }
}

}

回答1:

You just need to use an invisible button. First add a square button to your window. assign the desired key for it. make your button 0 pixels wide and 0 pixels height. Add an IBAction to your button and the code to be executed when the user press the key.

Another option is to addLocalMonitorForEventsMatchingMask for more info check this link

https://stackoverflow.com/a/32447474/2303865

回答2:

Try this code

override func viewDidLoad()
{
    super.viewDidLoad()

    NSEvent.addLocalMonitorForEventsMatchingMask(NSEventMask.KeyDownMask, handler: myKeyDownEvent)
}

func myKeyDownEvent(event: NSEvent) -> NSEvent
{
    print(event.keyCode)
    // Do stuff with keyCode. In my own projects I trap certain
    // keycodes.
    // If you want to block certain keycodes just change the return value
    // to an optional ->NSEvent? and return nil instead of event.
    return event
}

回答3:

Does your app even build?

NSEvent instances don't have a character property, they have a characters property. Using character should result in a failed build and an error message from Xcode. What's more characters returns an optional String whereas your switch cases are of type Int - this type-mismatch should result in a build failure also.

In my experience, the simplest way of finding out if any of the arrow keys are pressed is to switch on the event's keyCode property.

import Foundation
import Cocoa

let kLeftArrowKeyCode:  UInt16  = 123
let kRightArrowKeyCode: UInt16  = 124
let kDownArrowKeyCode:  UInt16  = 125
let kUpArrowKeyCode:    UInt16  = 126


class ViewController: NSViewController {

    override func keyDown(theEvent: NSEvent) {

        switch theEvent.keyCode {

        case kLeftArrowKeyCode:
            println(1)
        case kRightArrowKeyCode:
            println(2)
        case kDownArrowKeyCode:
            println(3)
        case kUpArrowKeyCode:
            println(4)
        default:
            break
        }
    }   
}

You can still use the predefined constants if you like, but these represent Unicode codes, so you'll need to convert them to a strings first, before you switch on characters.

回答4:

Ignoring the extra stuff about converting characters and the like, if your keyDown() function isn't even being called, the most probable reason is that you didn't tell the OS that your view can accept key events (via overriding acceptsFirstResponder).

Do this in the view class:

override var acceptsFirstResponder: Bool { get { return true } }

来源：https://stackoverflow.com/questions/29683910/keydown-doesnt-work-swift