Creating Swift Package with binaryTarget that has dependencies

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How can you distribute an XCFramework via Swift Package Manager when it has dependencies on other Swift packages? We accomplished this with CocoaPods in order to distribute our closed source SDK that has dependencies, but need to migrate to SPM. Note none of the types from the dependencies are used as part of our module’s public interface - usage is purely internal.

I’ve made a lot of progress following these steps for a simple example:

Create Framework Project

Create a new iOS Framework project in Xcode and name it WallpaperKit
In the project settings select the target and verify in Build Settings that Build Libraries for Distribution is Yes then set Skip Install to No
Create a new UIViewController subclass, name it WallpaperPreviewViewController, make it public, and add some functionality to it to show a UIImageView
Add a new Package Dependency in the project settings, for this example we’ll use https://github.com/onevcat/Kingfisher, and specify exact version 8.5.0
Add internal import Kingfisher and use it in WallpaperPreviewViewController to download and show an image from the web
Close the WallpaperKit project

Create Hosting App Project (this makes it easier to develop the framework functionality and test it in an app with Xcode building both in the same workspace)

Create a new iOS app project and name it WallpaperApp
Create a new workspace named WallpaperApp
Close the WallpaperApp project
Drag and drop WallpaperApp.xcodeproj into the workspace’s sidebar
Drag and drop WallpaperKit.xcodeproj into the workspace’s sidebar
Switch the scheme to WallpaperKit and build
Select WallpaperApp project, then with WallpaperApp target selected, in the General tab under Frameworks, Libraries, and Embedded Content, click + and add WallpaperKit.framework
In ViewController.swift, import WallpaperKit and add functionality to present an instance of WallpaperPreviewViewController
Run the app and verify it works

Create XCFramework

In Terminal, cd into WallpaperKit and run xcodebuild archive -scheme WallpaperKit -configuration Release -destination 'generic/platform=iOS' -archivePath './build/WallpaperKit.framework-iphoneos.xcarchive' SKIP_INSTALL=NO BUILD_LIBRARIES_FOR_DISTRIBUTION=YES DEFINES_MODULE=YES
Run xcodebuild archive -scheme WallpaperKit -configuration Release -destination 'generic/platform=iOS Simulator' -archivePath './build/WallpaperKit.framework-iphonesimulator.xcarchive' SKIP_INSTALL=NO BUILD_LIBRARIES_FOR_DISTRIBUTION=YES DEFINES_MODULE=YES
Run xcodebuild -create-xcframework -framework './build/WallpaperKit.framework-iphonesimulator.xcarchive/Products/Library/Frameworks/WallpaperKit.framework' -framework './build/WallpaperKit.framework-iphoneos.xcarchive/Products/Library/Frameworks/WallpaperKit.framework' -output './build/WallpaperKit.xcframework'
Open the build folder and retrieve the XCFramework

Create Swift Package

Create a new package in Xcode, select Library, and name it WallpaperKitDist
Drag and drop WallpaperKit.xcframework into Sources
Create a new directory in Sources called WallpaperKitDependencies
Create a new Swift file in WallpaperKitDependencies called WallpaperKitDependencies (SPM requires a Swift file to recognize WallpaperKitDependencies as a valid target and fetch dependencies)
Open Package.swift and change it to

import PackageDescription

let package = Package(
    name: "WallpaperKit",
    platforms: [
        .iOS(.v18)
    ],
    products: [
        .library(
            name: "WallpaperKit",
            targets: ["WallpaperKit", "WallpaperKitDependencies"]
        ),
    ],
    dependencies: [
        .package(
            url: "https://github.com/onevcat/Kingfisher.git",
            exact: "8.5.0"
        )
    ],
    targets: [
        .binaryTarget(
            name: "WallpaperKit",
            path: "./Sources/WallpaperKit.xcframework"
        ),
        .target(
            name: "WallpaperKitDependencies",
            dependencies: [
                "Kingfisher"
            ],
            path: "./Sources/WallpaperKitDependencies"
        )
    ]
)

Create Test App (to simulate a third-party app using the package)

Create a new iOS app project and name it TestApp
Add a new Local package selecting the WallpaperKitDist directory that contains Package.swift
Import WallpaperKit and use it to present a WallpaperPreviewViewController

This works! Though the console logs objc[39953]: Class _TtC10KingfisherP33_6AA794C9C370CDB07604B4D8B99AEAA312BundleFinder is implemented in both /Users/Name/Library/Developer/Xcode/DerivedData/TestApp-capvhjiqxrdgdnbevpkajicnjpcs/Build/Products/Debug-iphonesimulator/WallpaperKit.framework/WallpaperKit (0x100e8bbf8) and /Users/Name/Library/Developer/CoreSimulator/Devices/E0AF13C2-874C-47B9-B864-72AF3E4D5D4B/data/Containers/Bundle/Application/AF32011A-92E7-4E26-9A97-9F0C25C07863/TestApp.app/TestApp.debug.dylib (0x101a543b0). This may cause spurious casting failures and mysterious crashes. One of the duplicates must be removed or renamed.

I thought using internal import Kingfisher (or @_implementationOnly import Kingfisher) would have resolved this, but seems to make no difference compared to just import Kingfisher. I suspect it might not be an issue as long as the Kingfisher version number specified in the distribution Package.swift matches the version used in the framework project (and the app does not add a different version as a dependency), but not positive.

Can these warnings be resolved, or is it not a concern in this setup? Is this the best solution to distribute an XCFramework via Swift Package Manager that has dependencies on other Swift packages for now or is there a better approach? Thanks!

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