Added ability to enable/disable theming app-wide

Author: nfgrilo

Demo/Demo/AppDelegate.swift

@@ -17,6 +17,9 @@ class AppDelegate: NSObject, NSApplicationDelegate {
 
     func applicationWillFinishLaunching(_ notification: Notification) {
 
+        /* 0. Enable/disable theming capabilities. */
+        //ThemeManager.shared.isEnabled = false
+
         /* 1. Simpler usage: switch between light and dark theme directly. */
 
         //ThemeManager.lightTheme.apply()

Sources/NSColor+ThemeKit.swift

@@ -96,7 +96,7 @@ extension NSColor {
         themeKitSet()
 
         // check if the user provides an alternative color
-        if isThemeOverriden {
+        if ThemeManager.shared.isEnabled && isThemeOverriden {
             // call ThemeColor.set() function
             ThemeColor.color(with: Selector(colorNameComponent)).set()
         }
@@ -108,7 +108,7 @@ extension NSColor {
         themeKitSetFill()
 
         // check if the user provides an alternative color
-        if isThemeOverriden {
+        if ThemeManager.shared.isEnabled && isThemeOverriden {
             // call ThemeColor.setFill() function
             ThemeColor.color(with: Selector(colorNameComponent)).setFill()
         }
@@ -120,7 +120,7 @@ extension NSColor {
         themeKitSetStroke()
 
         // check if the user provides an alternative color
-        if isThemeOverriden {
+        if ThemeManager.shared.isEnabled && isThemeOverriden {
             // call ThemeColor.setStroke() function
             ThemeColor.color(with: Selector(colorNameComponent)).setStroke()
         }

Sources/ThemeManager.swift

@@ -33,29 +33,53 @@ public class ThemeManager: NSObject {
     private override init() {
         super.init()
 
-        // Initialize custom NSColor code (swizzle NSColor, if needed)
-        NSColor.swizzleNSColor()
+        isEnabled = true
+    }
 
-        // Observe and theme new windows (before being displayed onscreen)
-        self.obj = NotificationCenter.default.addObserver(forName: NSWindow.didUpdateNotification, object: nil, queue: nil) { (notification) in
-            if let window = notification.object as? NSWindow {
-                window.themeIfCompliantWithWindowThemePolicy()
-            }
+    deinit {
+        isEnabled = false
+    }
+
+    /// Enables or disables ThemeKit functionality.
+    @objc public var isEnabled: Bool {
+        get {
+            return _isEnabled ?? false
         }
+        set {
+            guard _isEnabled != newValue else { return }
+            _isEnabled = newValue
+
+            // enable
+            if newValue {
+                // Initialize custom NSColor code (swizzle NSColor, if needed - done only once)
+                NSColor.swizzleNSColor()
+
+                // Observe and theme new windows (before being displayed onscreen)
+                self.obj = NotificationCenter.default.addObserver(forName: NSWindow.didUpdateNotification, object: nil, queue: nil) { (notification) in
+                    if let window = notification.object as? NSWindow {
+                        window.themeIfCompliantWithWindowThemePolicy()
+                    }
+                }
 
-        // Observe current theme on User Defaults
-        NSUserDefaultsController.shared.addObserver(self, forKeyPath: themeChangeKVOKeyPath, options: NSKeyValueObservingOptions(rawValue: 0), context: nil)
+                // Observe current theme on User Defaults
+                NSUserDefaultsController.shared.addObserver(self, forKeyPath: themeChangeKVOKeyPath, options: NSKeyValueObservingOptions(rawValue: 0), context: nil)
 
-        // Observe current system theme (macOS Apple Interface Theme)
-        NotificationCenter.default.addObserver(self, selector: #selector(systemThemeDidChange(_:)), name: .didChangeSystemTheme, object: nil)
-    }
+                // Observe current system theme (macOS Apple Interface Theme)
+                NotificationCenter.default.addObserver(self, selector: #selector(systemThemeDidChange(_:)), name: .didChangeSystemTheme, object: nil)
+            }
 
-    deinit {
-        if let object = self.obj {
-          NotificationCenter.default.removeObserver(object)
+            // disable
+            else {
+                if let object = self.obj {
+                    NotificationCenter.default.removeObserver(object)
+                }
+                NSUserDefaultsController.shared.removeObserver(self, forKeyPath: themeChangeKVOKeyPath)
+                NotificationCenter.default.removeObserver(self, name: .didChangeSystemTheme, object: nil)
+            }
         }
-        NSUserDefaultsController.shared.removeObserver(self, forKeyPath: themeChangeKVOKeyPath)
     }
+    /// Internal storage for `isEnabled` property.
+    private var _isEnabled: Bool?
 
     // MARK: -
     // MARK: Themes
@@ -69,6 +93,8 @@ public class ThemeManager: NSObject {
             return _theme ?? ThemeManager.defaultTheme
         }
         set(newTheme) {
+            guard isEnabled else { return }
+
             // Apply theme
             if _theme == nil || newTheme.effectiveTheme != _theme! || newTheme.effectiveTheme.isUserTheme {
                 applyTheme(newTheme)
@@ -208,6 +234,8 @@ public class ThemeManager: NSObject {
     /// Get last applied theme from user defaults and load it. If no theme was
     /// previously applied, load the default theme (`ThemeManager.defaultTheme`).
     @objc public func applyLastOrDefaultTheme() {
+        guard isEnabled else { return }
+
         let userDefaultsTheme = theme(withIdentifier: UserDefaults.standard.string(forKey: ThemeManager.userDefaultsThemeKey))
         (userDefaultsTheme ?? ThemeManager.defaultTheme).apply()
     }
@@ -444,6 +472,7 @@ public class ThemeManager: NSObject {
 
     /// Apply a new `theme`.
     private func applyTheme(_ newTheme: Theme) {
+        guard isEnabled else { return }
 
         // Make theme effective
         func makeThemeEffective(_ newTheme: Theme) {