Context

Consider a simple Swift Package with a MyLibrary and MyExecutable target.
The aim is for MyExecutable to use MyLibrary (which has an image).

The MyLibrary target has 2 files, a Resources/Assets.xcassets catalog (with 1 image named “Test”) and an Images.swift file like so:

private extension NSImage {
    static let test = Bundle.module.image(forResource: "Test")
}

public struct Images {
    public static func printTestExists() {
        print("Exists: (NSImage.test != nil)")
    }
}

Please note in particular the use of Bundle.module here. The MyExecutable consists of merely a main.swift file that imports MyLibrary and runs:

Images.printTestExists()

Issue

When running the MyExecutable scheme in Xcode, it works as expected printing:

Exists: true

However, when running the executable from the command line:

swift run -c release MyExecutable

it crashes with the error:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSBundle imageForResource:]: unrecognized selector sent to instance

Question

Why do assets seem not to work from the command-line? I’m only executing the swift run command so the executable file should have access to the library bundle, right?

Package.swift

The assets are processed as a resource as you would expect

let package = Package(
    name: "MyLibrary",
    platforms: [.macOS(.v13)],
    products: [
        .library(name: "MyLibrary", targets: ["MyLibrary"]),
        .executable(name: "MyExecutable", targets: ["MyExecutable"])
    ],
    targets: [
        .target(name: "MyLibrary", resources: [.process("Resources")] ),
        .executableTarget(name: "MyExecutable", dependencies: ["MyLibrary"])
    ]
)

Aside

Using the following SwiftUI code from the command-line would similarly not show an image but works when run from Xcode:

Image("Test", bundle: .module)

Attachments

References

I found a similar issue on Swift forums