Setting backgroundColor of custom NSView

问题

What is the process of drawing to NSView using storyboards for osx? I have added a NSView to the NSViewController. Then, I added a few constraints and an outlet.

Next, I added some code to change the color: import Cocoa

class ViewController: NSViewController {

    @IBOutlet var box: NSView!

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func viewWillAppear() {
        box.layer?.backgroundColor = NSColor.blueColor().CGColor
        //box.layer?.setNeedsDisplay()
    }

    override var representedObject: AnyObject? {
        didSet {
        // Update the view, if already loaded.
        }
    } 
}

I would like to do custom drawing and changing colors of the NSView. I have performed sophisticated drawing on iOS in the past, but am totally stuck here. Does anyone see what I'm doing wrong?

回答1:

The correct way is

class ViewController: NSViewController {

@IBOutlet var box: NSView!

override func viewDidLoad() {
    super.viewDidLoad()
    self.view.wantsLayer = true

}

override func viewWillAppear() {
    box.layer?.backgroundColor = NSColor.blue.cgColor
    //box.layer?.setNeedsDisplay()
}

override var representedObject: AnyObject? {
    didSet {
    // Update the view, if already loaded.
    }
}}

回答2:

Swift via property

extension NSView {

    var backgroundColor: NSColor? {
        get {
            if let colorRef = self.layer?.backgroundColor {
                return NSColor(CGColor: colorRef)
            } else {
                return nil
            }
        }
        set {
            self.wantsLayer = true
            self.layer?.backgroundColor = newValue?.CGColor
        }
    }   
}

Usage:

    yourView.backgroundColor = NSColor.greenColor()

Where yourView is NSView or any of its subclasses

Updated for Swift 3

extension NSView {

    var backgroundColor: NSColor? {

        get {
            if let colorRef = self.layer?.backgroundColor {
                return NSColor(cgColor: colorRef)
            } else {
                return nil
            }
        }

        set {
            self.wantsLayer = true
            self.layer?.backgroundColor = newValue?.cgColor
        }
    }
}

回答3:

edit/update:

Another option is to design your own colored view:

import Cocoa
@IBDesignable class ColoredView: NSView {
    @IBInspectable var backgroundColor: NSColor = .clear
    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)
        backgroundColor.set()
        dirtyRect.fill()
    }
}

Then you just need to add a Custom View NSView and set the custom class in the inspector:

---

Original Answer

Swift 3.0 or later

extension NSView {
    var backgroundColor: NSColor? {
        get {
            guard let color = layer?.backgroundColor else { return nil }
            return NSColor(cgColor: color)
        }
        set {
            wantsLayer = true
            layer?.backgroundColor = newValue?.cgColor
        }
    }
}

let myView = NSView(frame: NSRect(x: 0, y: 0, width: 100, height: 100))
myView.backgroundColor = .red

回答4:

This works a lot better:

    override func drawRect(dirtyRect: NSRect) {
        super.drawRect(dirtyRect)
        NSColor.blueColor().setFill()
        NSRectFill(dirtyRect);
    }

回答5:

Best way to set a NSView background colour in MacOS 10.14 with dark mode support :

1/ Create your colour in Assets.xcassets

2/ Subclass your NSView and add this :

class myView: NSView {
    override func updateLayer() {
       self.layer?.backgroundColor = NSColor(named: "customControlColor")?.cgColor
    }
}

Very simple and dark mode supported with the colour of your choice !

Full guide : https://developer.apple.com/documentation/appkit/supporting_dark_mode_in_your_interface

回答6:

Update to Swift 3 solution by @CryingHippo (It showed colors not on every run in my case). I've added DispatchQueue.main.async and now it shows colors on every run of the app.

extension NSView {

    var backgroundColor: NSColor? {

        get {
            if let colorRef = self.layer?.backgroundColor {
                return NSColor(cgColor: colorRef)
            } else {
                return nil
            }
        }

        set {

            DispatchQueue.main.async { 

                self.wantsLayer = true
                self.layer?.backgroundColor = newValue?.cgColor

            }

        }
    }
}

回答7:

Since macOS 10.13 (High Sierra) NSView responds to selector backgroundColor although it is not documented!

来源：https://stackoverflow.com/questions/27890144/setting-backgroundcolor-of-custom-nsview