Animated dark mode transition

animate_dark.swift

// swiftc this file & mv to /usr/local/bin
import Cocoa 

typealias NSGlobalPreferenceTransitionBlock = @convention(block) () -> Void
@objc protocol NSGlobalPreferenceTransitionProtocol: NSObjectProtocol {  
  static func transition() -> AnyObject
  func waitForTransitionWithCompletionHandler(_ arg1: @escaping NSGlobalPreferenceTransitionBlock)
  func postChangeNotification(_ arg1: UInt64, completionHandler arg2: @escaping NSGlobalPreferenceTransitionBlock)
}
let NSGlobalPreferenceTransition: AnyClass = NSClassFromString("NSGlobalPreferenceTransition")!

let libSkyLight = dlopen("/System/Library/PrivateFrameworks/SkyLight.framework/Skylight", RTLD_LAZY)
let SLSGetAppearanceThemeLegacy = unsafeBitCast(dlsym(
  libSkyLight,
  "SLSGetAppearanceThemeLegacy"
), to: (@convention (c) () -> Bool).self)
let SLSSetAppearanceThemeLegacy = unsafeBitCast(dlsym(
  libSkyLight,
  "SLSSetAppearanceThemeLegacy"
), to: (@convention (c) (Bool) -> Void).self)
let SLSSetAppearanceThemeNotifying = unsafeBitCast(dlsym(
  libSkyLight,
  "SLSSetAppearanceThemeNotifying"
), to: (@convention (c) (Bool, Bool) -> Void).self)

DispatchQueue.main.async {
	SLSSetAppearanceThemeNotifying(!SLSGetAppearanceThemeLegacy(), false)
	let transition: AnyObject? = NSGlobalPreferenceTransition.transition()
	transition?.postChangeNotification(0, completionHandler: {})
	transition?.waitForTransitionWithCompletionHandler { exit(0) }
}
NSApplication.shared.run()