How can dark mode be detected on macOS 10.14?

Question

In macOS 10.14 users can choose to adopt a system-wide light or dark appearance and I need to adjust some colours manually depend of the current mode.

Answer 1

I have used the current appearance checking if the system is 10.14

+ (BOOL)isDarkMode {
    NSAppearance *appearance = NSAppearance.currentAppearance;
    if (@available(*, macOS 10.14)) {
        return appearance.name == NSAppearanceNameDarkAqua;
    }

    return NO;
}

And to detect the change of mode in a view the methods are:

- (void)updateLayer;
- (void)drawRect:(NSRect)dirtyRect;
- (void)layout;
- (void)updateConstraints;

And to detect the change of mode in a view controller the methods are:

- (void)updateViewConstraints;
- (void)viewWillLayout;
- (void)viewDidLayout;

Using notification:

// Monitor menu/dock theme changes...
[NSDistributedNotificationCenter.defaultCenter addObserver:self selector:@selector(themeChanged:) name:@"AppleInterfaceThemeChangedNotification" object: nil];

-(void)themeChanged:(NSNotification *) notification {
    NSLog (@"%@", notification);
}

For more information Dark Mode Documentation