DSFAppearanceManager

A class for simplifying macOS appearance values and detecting setting changes (Swift/Objective-C).

Why?

If you're performing custom drawing within your macOS app, it's important to obey the user's display and accessibility settings when performing your drawing so you can adapt accordingly.

Secondly, when the user changes their settings (eg. when the system changes automatically light/dark modes) I wanted my app to be notified of the change so I can update the drawing to match the new setting(s).

Appearance

DSFAppearanceManager has a number of properties to simplify macOS appearance settings

Available properties

These are the static properties available on the DSFAppearanceManager

So, for example, to get the current macOS highlight color, call DSFAppearanceManager.HighlightColor.

Change detection

You can ask to be notified when appearance settings changes.

Declare a variable of type DSFAppearanceManager.ChangeDetector()

private let appearanceChangeDetector = DSFAppearanceManager.ChangeDetector()

... and set the callback block.

appearanceChangeDetector.appearanceChangeCallback = { [weak self] manager, change in
	// Handle the change here.
	// `change` contains the _types_ of change(s) that occurred. 
	//  This might be theme, accent, contrastOrAccessibility etc
	let newColor = manager.accentColor
	...
}

Done!

Change detection types

The change object will indicate the type of change that occurred.

Note that the change detection class debounces changes to reduce the number of callbacks when a change occurs. The change object passed in the callback block contains a set of the changes that occurred.

Objective-C support

@interface ViewController ()
@property(nonatomic, strong) DSFAppearanceManagerChangeDetector* detector;
@end

@implementation ViewController
- (void)viewDidAppear {
   [super viewDidAppear];
   [self setDetector: [[DSFAppearanceManagerChangeDetector alloc] init]];
   [[self detector] setAppearanceChangeCallback:^(DSFAppearanceManager * _Nonnull manager, DSFAppearanceManagerChange * _Nonnull change) {
      // Change detected! Do something to update display
   }];
}
@end

Additional info

NSView appearance drawing

DSFAppearanceManager provides extensions to NSView as a convenience for automatically handling the view's effective drawing appearance.

func drawRect(_ dirtyRect: CGRect) {
   ...
   self.performUsingEffectiveAppearance { appearance in
      // Do your drawing using 'appearance'
      // Requests for dynamic colors etc. will automatically use the correct appearance for the view.
   }
}

Rolling your own dynamic NSColor

If you can't use the Assets.xcassets to store your dynamic NSColors (or you want to move your app's configuration into code) you'll find that the default NSColor doesn't have much support for automatically handling light/dark mode changes.

Dusk is a small swift framework to aid in supporting Dark Mode on macOS. It provides an NSColor subclass (DynamicColor) that automatically provides light/dark mode variants when required.

lazy var c1 = DynamicColor(name: "uniqueColorName") { (appearance) in 
    // return the color to use for this appearance
}

let c1 = DynamicColor(name: "uniqueColorName", lightColor: NSColor.white, darkColor: NSColor.black)

And because DynamicColor inherits from NSColor, it can be used wherever NSColor can be used.

Thanks!

ChimeHQ for developing the awesome dynamic NSColor subclass.

License

MIT. Use it and abuse it for anything you want, just attribute my work. Let me know if you do use it somewhere, I'd love to hear about it!

MIT License

Copyright (c) 2022 Darren Ford

Permission is hereby granted, free of charge, to any person obtaining a copy
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The above copyright notice and this permission notice shall be included in all
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