1.给View添加一个extension,分别给四个平台添加一个方法

extension View {
    func iOS<Content: View>(_ modifier: (Self) -> Content) -> some View {
        #if os(iOS)
        return modifier(self)
        #else
        return self
        #endif
    }
}

extension View {
    func macOS<Content: View>(_ modifier: (Self) -> Content) -> some View {
        #if os(macOS)
        return modifier(self)
        #else
        return self
        #endif
    }
}

extension View {
    func tvOS<Content: View>(_ modifier: (Self) -> Content) -> some View {
        #if os(tvOS)
        return modifier(self)
        #else
        return self
        #endif
    }
}

extension View {
    func watchOS<Content: View>(_ modifier: (Self) -> Content) -> some View {
        #if os(watchOS)
        return modifier(self)
        #else
        return self
        #endif
    }
}

应用示例:

Text("Hello World")
    .iOS { $0.padding(10) }

原文:https://www.hackingwithswift.com/quick-start/swiftui/swiftui-tips-and-tricks