如何在 swift 包管理器中使目标产品平台特定

Question

我有以下总体架构。一个为我的所有模型数据导入 Swift 包的应用程序，然后根据平台与 Firestore 一起使用或直接 REST 到 firestore。我对 WatchOS 部分使用 REST，因为 firestore-swift 仍然不支持 WatchOS。

我的 Swift 包依赖于 Firestore，这不是问题。但是，我只希望目标部分中的目标可用于 iOS 和 MacOS，而不包含在 WatchOS 上。我可以在包清单文件中指定它吗？

这是我正在尝试做的事情的总体图表。

我的包清单如下所示。请注意底部的两行注释掉的行，我只想在目标是 iOS 或 MacOS 时才包含它们。

// swift-tools-version:5.5
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "EMobileLibrary",
    platforms: [.iOS(.v15), .watchOS(.v8), .macOS(.v12)],
    products: [
        // Products define the executables and libraries a package produces, and make them visible to other packages.
        .library(
            name: "EMobileLibrary",
            targets: ["EMobileLibrary"]),
    ],
    dependencies: [
        // Dependencies declare other packages that this package depends on.
        .package(name: "AppDevWithSwiftLibrary", url: "https://github.com/directoryname/AppDevWithSwiftLibrary", from: "1.11.6"),
        .package(
            name: "Firebase",
            url: "https://github.com/firebase/firebase-ios-sdk.git",
            .upToNextMajor(from: "8.10.0")
          ),
    ],
    targets: [
        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
        // Targets can depend on other targets in this package, and on products in packages this package depends on.
        .target(
            name: "EMobileLibrary",
            dependencies: [
                .product(name: "AppDevWithSwiftLibrary", package: "AppDevWithSwiftLibrary"),
//                .product(name: "FirebaseFirestore", package: "Firebase"),
//                .product(name: "FirebaseFirestoreSwift-Beta", package: "Firebase")
            ]
        ),
        .testTarget(
            name: "EMobileLibraryTests",
            dependencies: ["EMobileLibrary"]),
    ]
)

Answer 1

定义具有平台相关依赖性的虚拟包装器目标。

以下是https://github.com/firebase/firebase-ios-sdk/blob/master/Package.swift的示例摘录，它将 FirebaseDynamicLinks 定义为仅在 iOS 上可用，但在 tvOS、macOS 或 watchOS 上不可用：

    .library(
      name: "FirebaseDynamicLinks",
      targets: ["FirebaseDynamicLinksTarget"]
    ),
.
.
.
    .target(
      name: "FirebaseDynamicLinksTarget",
      dependencies: [.target(name: "FirebaseDynamicLinks",
                             condition: .when(platforms: [.iOS]))],
      path: "SwiftPM-PlatformExclude/FirebaseDynamicLinksWrap"
    ),

    .target(
      name: "FirebaseDynamicLinks",
       ....