Swift Package Manager本地包依赖层级构建及依赖访问问题求助

包结构与当前配置 #

Core包（Package A） #

作为核心包，包含主要原生代码及外部依赖，配置如下：

let package = Package(
    name: "Core",
    platforms: [
      .iOS(.v14)
    ],
    products: [
        .library(
            name: "Core",
            targets: ["Core"]),
    ],
    dependencies: [
      .package(url: "https://github.com/mxcl/PromiseKit", .exact("6.13.1")),
      .package(url: "https://github.com/PromiseKit/Foundation.git", from: "3.0.0"),
    ],
    targets: [
        .target(
            name: "Core",
            dependencies: [
                           .product(name: "PMKFoundation", package: "Foundation"),
                           "PromiseKit",
                          ]),
        .testTarget(
            name: "CoreTests",
            dependencies: ["Core"]),
    ]
)

Package B #

依赖本地Core包，需访问Core使用的外部依赖，当前配置：

let package = Package(
    name: "Package_B",
    platforms: [
      .iOS(.v14)
    ],
    products: [
        .library(
            name: "Package_B",
            targets: ["Package_B"]),
    ],
    dependencies: [
      .package(path: "../Core"),
    ],
    targets: [
        .target(
            name: "Package_B",
            dependencies: [
              "Core",
              "PromiseKit",
            ]),
        .testTarget(
            name: "Package_BTests",
            dependencies: ["Package_B"]),
    ]
)

Package C #

依赖Package B，需访问Package B、Core及Core的外部依赖，当前配置：

let package = Package(
    name: "Package_C",
    products: [
        .library(
            name: "Package_C",
            targets: ["Package_C"]),
    ],
    dependencies: [
      .package(path: "../Package_B"),
      .package(url: "https://github.com/ZipArchive/ZipArchive.git", from: "2.2.0"),
    ],
    targets: [
        .target(
            name: "Package_C",
            dependencies: ["Core","Package_B", "PromiseKit", "ZipArchive"]),
        .testTarget(
            name: "Package_CTests",
            dependencies: ["Package_C"]),
    ]
)

遇到的错误 #

1. Package B编译报错：

x-xcode-log://7C2F67D1-F6A1-4BE1-8E94-DC7E769241AD product 'PromiseKit' required by package 'Package_B' target 'Package_B' not found.

2. 添加PromiseKit的package依赖到Package B后，出现导入错误：

No such module 'PromiseKit'
No such module 'Core'

问题根源 #

SPM中，子包直接写外部依赖名称（如"PromiseKit"）时，会优先在自身的package依赖列表中查找对应包，而非自动使用上层包的传递依赖。重复添加外部依赖还可能导致版本冲突，同时路径配置或缓存问题也会引发模块找不到的错误。

正确配置方案 #

1. 修正Package B的依赖引用 #

无需在Package B的dependencies中重复添加PromiseKit的package，而是通过Core的传递依赖来引用，修改target的依赖写法：

let package = Package(
    name: "Package_B",
    platforms: [
      .iOS(.v14)
    ],
    products: [
        .library(
            name: "Package_B",
            targets: ["Package_B"]),
    ],
    dependencies: [
      .package(path: "../Core"),
    ],
    targets: [
        .target(
            name: "Package_B",
            dependencies: [
              "Core",
              // 通过传递依赖引用PromiseKit，指定包名而非路径
              .product(name: "PromiseKit", package: "PromiseKit")
            ]),
        .testTarget(
            name: "Package_BTests",
            dependencies: ["Package_B"]),
    ]
)

2. 修正Package C的依赖引用 #

Package C无需直接添加Core的路径依赖（通过Package B的传递依赖即可获取），同时统一平台版本，避免冲突：

let package = Package(
    name: "Package_C",
    platforms: [.iOS(.v14)],
    products: [
        .library(
            name: "Package_C",
            targets: ["Package_C"]),
    ],
    dependencies: [
      .package(path: "../Package_B"),
      .package(url: "https://github.com/ZipArchive/ZipArchive.git", from: "2.2.0"),
    ],
    targets: [
        .target(
            name: "Package_C",
            dependencies: [
                "Package_B",
                // 通过传递依赖引用Core
                .product(name: "Core", package: "Core"),
                // 通过传递依赖引用PromiseKit
                .product(name: "PromiseKit", package: "PromiseKit"),
                .product(name: "ZipArchive", package: "ZipArchive")
            ]),
        .testTarget(
            name: "Package_CTests",
            dependencies: ["Package_C"]),
    ]
)

3. 辅助排查步骤 #

• 统一所有包的platforms版本，避免因平台不一致导致的依赖解析失败；
• 清理Xcode缓存：选择File > Packages > Reset Package Caches，再执行File > Packages > Update to Latest Package Versions；
• 确认本地包的相对路径正确（如../Core是否指向Core包的实际位置）。

内容的提问来源于stack exchange，提问作者kivu