一种简单的 iOS 暗黑模式实现方案(支持低版本)

swift

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enum Theme: Int, CaseIterable {
    case none = 0
    case light = 1
    case dark = 2

    var title: String {
        switch self {
            case .none: return "Follow"
            case .light: return "Light"
            case .dark: return "Dark"
        }
    }

    @available(iOS 13.0, *)
    var mode: UIUserInterfaceStyle {
        switch self {
            case .none: return .unspecified
            case .light: return .light
            case .dark: return .dark
        }
    }
}

swift

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class Tools {
    @UserDefaultStorage(keyName: "appTheme")
    static var _style: Int? // 此处用于全局存储 UserDefaults 属性

    static var style: Theme {
        get { return Theme(rawValue: (_style ?? 0)) ?? .dark }
        set { _style = newValue.rawValue }
    }

    /// 创造颜色, 核心方法
    static func makeColor(light: UIColor, dark: UIColor) -> UIColor {
        if #available(iOS 13.0, *) {
            return UIColor { $0.userInterfaceStyle == .light ? light : dark }
        } else {
            return Tools.style == .light ? light : dark
        }
    }

    /// 创造 img, 核心方法
    static func makeImage(light: UIImage, dark: UIImage) -> UIImage {
        if #available(iOS 13.0, *) {
            let image = UIImage()
            image.imageAsset?.register(light, with: .init(userInterfaceStyle: .light))
            image.imageAsset?.register(dark, with: .init(userInterfaceStyle: .dark))
            return image
        } else {
            return Tools.style == .light ? light : dark
        }
    }

swift

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func changeTheme(theme: Theme) {
    Tools.style = theme
    guard let window = UIWindow.hl.getKeyWindow() else { return }
    if #available(iOS 13.0, *) {
        window.overrideUserInterfaceStyle = theme.mode
    } else {
        guard let rootVC = window.rootViewController else { return }
        let tabbar = Tools.setTabVC(withIndex: self.index)
        window.rootViewController = tabbar
    }
}

swift

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func application(_ application: UIApplication,
                 didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?)
                 -> Bool {

    window = UIWindow(frame: UIScreen.main.bounds)

    // 如果是 iOS
    if #available(iOS 13.0, *) {
        window?.overrideUserInterfaceStyle = Tools.style.mode
    }

    window?.rootViewController = Tools.getTabVC(withIndex: 0)
    window?.makeKeyAndVisible()

    return true
}