SwiftUI 的换肤功能

如图：
[图片上传失败...(image-116cfb-1679038440320)]

因为老项目突然要加上一键换肤，做完老项目后，抽空用SwifUI 再实现一遍，感觉上要比UIkit框架要简单的多了。不多说上代码:
首先定义一个枚举Theme, 里面实现一些方法

enum SFAppTheme: String{
    case Red_APP_Theme      = "red"
    case Blue_APP_Theme     = "blue"
    case Green_APP_Theme    = "green"
    case Yellow_APP_Theme   = "yellow"
    
    func homeBg() -> String {
        switch self {
        case .Red_APP_Theme:
            return "bg04"
        case .Blue_APP_Theme:
            return "bg01"
        case .Green_APP_Theme:
            return "bg02"
        case .Yellow_APP_Theme:
            return "bg03"
        }
    }
    
    func setPageBg() -> String {
        switch self {
        case .Red_APP_Theme:
            return "set_bg04"
        case .Blue_APP_Theme:
            return "set_bg01"
        case .Green_APP_Theme:
            return "set_bg02"
        case .Yellow_APP_Theme:
            return "set_bg03"
        }
    }
    
    func themeColor() -> Color {
        switch self {
        case .Red_APP_Theme:
            return Color("AppRed")
        case .Blue_APP_Theme:
            return Color("AppBlue")
        case .Green_APP_Theme:
            return Color("AppGreen")
        case .Yellow_APP_Theme:
            return Color("AppYellow")
        }
    }
    
    
    static func nowTheme() -> SFAppTheme {
        guard let theme:String = UserDefaults.standard.string(forKey: "SFAppThemeKey") else{
            return .Red_APP_Theme
        }
        guard let nowThemeType = SFAppTheme(rawValue: theme) else{
            return .Red_APP_Theme
        }
        return nowThemeType
    }
}

然后定义一个APPState 用来存储app的状态值所用:

class APPState:ObservableObject{
    @Published var appTheme:SFAppTheme = .Red_APP_Theme
    init() {
        //创建imei
        let sfDevice = SFDevice()
        sfDevice.creatImei()
        appTheme = SFAppTheme.nowTheme()
    }
    
    
    func setTheme(theme:SFAppTheme){
        UserDefaults.standard.setValue(theme.rawValue, forKey: "SFAppThemeKey")
        self.appTheme = theme
    }
}

最后再app入口地方注入：

@main
struct seaSoftDRPSwiftUiApp: App {
    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
    @StateObject var appState:APPState = APPState() //APP的全局状态 可以切换主题啥的 environmentObject注入到全局中
    
    var body: some Scene {
        WindowGroup {
            LaunchView()
                .environmentObject(appState)
        }
    }
}

用的时候：

@EnvironmentObject var appState:APPState

 .background(
            appState.appTheme.themeColor()
                .frame(width: screenWidth)
                .ignoresSafeArea(.all,edges: .top)
        )

  Button {
                        appState.setTheme(theme: .Red_APP_Theme)
                    } label: {
                        Text("切换主题红色")
                    }

这样即可实现一键换肤，
需要注意这里的定义Color因为要适配黑暗模式，是在Assets里自己添加的Color Set 如下图：
[图片上传失败...(image-406ab1-1679038440320)]

如果也需要修改纯色图片，那么可以让UI给你一个SVG图片，然后在 Assets里设置图片的RenderModel为
Template Image。就可以直接用 ：foregroundColor 直接给图片着色
[图片上传失败...(image-2010f5-1679038440320)]

 Image(type.barName())
                    .resizable()
                    .frame(width: 25,height: 25)
                    .foregroundColor(viewModel.selectedTab == type ? appState.appTheme.themeColor() : Color(hex: "999999"))

如果不是纯色图片，就麻烦点，我这里有个就是不是纯色图片，用的枚举返回的，上诉代码里的：

   func setPageBg() -> String {
        switch self {
        case .Red_APP_Theme:
            return "set_bg04"
        case .Blue_APP_Theme:
            return "set_bg01"
        case .Green_APP_Theme:
            return "set_bg02"
        case .Yellow_APP_Theme:
            return "set_bg03"
        }
    }

希望能帮到纠结的小伙伴～