Initial commit.

.swiftlint.yml

@@ -17,5 +17,11 @@ excluded: # paths to ignore during linting. Takes precedence over `included`.
   - Tests
   - Example
 
-disabled_rules: # rule identifiers to exclude from running
-  - trailing_whitespace
+identifier_name:
+  min_length: # only min_length
+    error: 4 # only error
+  excluded: # excluded via string array
+    - id
+
+nesting:
+  type_level: 2

Example/AppDelegate.swift

@@ -1,10 +1,4 @@
-//
-//  AppDelegate.swift
-//  Example
-//
-//  Created by Łukasz Śliwiński on 30 Apr 2020.
-//  Copyright © 2020 plum. All rights reserved.
-//
+// Copyright © 2020 plum. All rights reserved.
 
 import UIKit
 
@@ -28,8 +22,10 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     ///   - application: The UIApplication
     ///   - launchOptions: The LaunchOptions
     /// - Returns: The launch result
-    func application(_ application: UIApplication,
-                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
+    func application(
+        _ application: UIApplication,
+        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
+    ) -> Bool {
         // Initialize UIWindow
         self.window = .init(frame: UIScreen.main.bounds)
         // Set RootViewController

Example/Stylesheet.swift

@@ -0,0 +1,86 @@
+// Copyright © 2020 plum. All rights reserved.
+
+import UIKit
+import ObservableThemeKit
+
+// MARK: - Stylesheet
+
+/// For the sake of the example Stylesheet represents what kind of the Style type, the Theme could hold
+struct Stylesheet {
+
+    fileprivate static var shared: Observable<Stylesheet> = .init(Stylesheet(appearance: .light))
+
+    let appearance: Appearance
+    let primaryColor: UIColor
+    let backgroundColor: UIColor
+
+    init(appearance: Appearance) {
+        self.appearance = appearance
+
+        switch appearance {
+        case .light:
+            self.primaryColor = .black
+            self.backgroundColor = .white
+        case .dark:
+            self.primaryColor = .white
+            self.backgroundColor = .darkGray
+        }
+    }
+
+    func font(with type: FontType) -> UIFont {
+        switch type {
+        case .header:
+            return UIFont.systemFont(ofSize: 16, weight: .semibold)
+        case .normal:
+            return UIFont.systemFont(ofSize: 14, weight: .regular)
+        case .small:
+            return UIFont.systemFont(ofSize: 10, weight: .regular)
+        }
+    }
+}
+
+// MARK: - Stylesheet helpers
+
+extension Stylesheet {
+
+    /// Change shared stylesheet using the new appearance
+    static func changeAppearance(to appearance: Appearance) {
+        Self.shared.wrappedValue = Stylesheet(appearance: appearance)
+    }
+
+    /// Currently used appearance in the stylesheet
+    static var appearance: Appearance {
+        return Self.shared.wrappedValue.appearance
+    }
+
+    /// Currently set stylesheet
+    static var current: Stylesheet {
+        return Self.shared.wrappedValue
+    }
+}
+
+// MARK: - Stylesheet types
+
+extension Stylesheet {
+
+    enum Appearance {
+        case light
+        case dark
+    }
+
+    enum FontType {
+        case header
+        case normal
+        case small
+    }
+}
+
+// MARK: - Theme default implementation
+
+extension Theme {
+
+    /// Default stylesheet for the convenience
+    static var stylesheet: Observable<Stylesheet> {
+        return Stylesheet.shared
+    }
+}

Example/ViewController.swift

@@ -1,43 +1,81 @@
-//
-//  ViewController.swift
-//  Example
-//
-//  Created by Łukasz Śliwiński on 30 Apr 2020.
-//  Copyright © 2020 plum. All rights reserved.
-//
+// Copyright © 2020 plum. All rights reserved.
 
-import UIKit
 import ObservableThemeKit
+import UIKit
 
 // MARK: - ViewController
 
 /// The ViewController
 class ViewController: UIViewController {
 
     // MARK: Properties
-    
-    /// The Label
-    lazy var label: UILabel = {
-        let label = UILabel()
-        label.text = "🚀\nObservableThemeKit\nExample"
-        label.font = .systemFont(ofSize: 25, weight: .semibold)
-        label.numberOfLines = 0
-        label.lineBreakMode = .byWordWrapping
-        label.textAlignment = .center
-        return label
+
+    /// Theme
+    @ObservableTheme var theme: ViewTheme
+
+    /// Button
+    lazy var button: UIButton = {
+        let button = UIButton()
+        button.setTitle("Change appearance", for: .normal)
+        button.addTarget(self, action: #selector(handleButtonTap), for: .touchUpInside)
+        return button
     }()
-    
+
     // MARK: View-Lifecycle
-    
+
     /// View did load
     override func viewDidLoad() {
         super.viewDidLoad()
-        self.view.backgroundColor = .white
+        self.setupAppearance()
+
+        self.$theme.observe(
+            owner: self,
+            handler: { (owner, _) in
+                owner.setupAppearance()
+            }
+        )
     }
-    
-    /// LoadView
+
+    /// Load view
     override func loadView() {
-        self.view = self.label
+        self.view = self.button
     }
 
+    // MARK: Helpers
+
+    /// Setup appearance
+    private func setupAppearance() {
+        self.button.setTitleColor(theme.labelColor, for: .normal)
+        self.button.titleLabel?.font = theme.buttonFont
+        self.view.backgroundColor = theme.backgroundColor
+    }
+
+    /// Handle button tap
+    @objc private func handleButtonTap() {
+        if Stylesheet.appearance == .light {
+            Stylesheet.changeAppearance(to: .dark)
+        } else {
+            Stylesheet.changeAppearance(to: .light)
+        }
+    }
+}
+
+// MARK: - ViewTheme
+
+extension ViewController {
+
+    /// Theme for the ViewController
+    struct ViewTheme: Theme {
+        static let `default`: ViewController.ViewTheme = .init(stylesheet: Self.stylesheet.wrappedValue)
+
+        let labelColor: UIColor
+        let backgroundColor: UIColor
+        let buttonFont: UIFont
+
+        init(stylesheet: Stylesheet) {
+            self.labelColor = stylesheet.primaryColor
+            self.backgroundColor = stylesheet.backgroundColor
+            self.buttonFont = stylesheet.font(with: .header)
+        }
+    }
 }