SPM fails to load the library as a sub-dependency

[via-guy]

Our app was referencing a private Analytics library that was referencing the mParticle SDK, and we were getting a lot of failures in our CI/CD where our app failed to build because the Analytics library failed to find the binary SDK. This required us to convert back to CocoaPods.

Has anyone else had this issue?

I investigated ways to solve this, and there were 2 options:

First is to change Package.swift to provide the source code instead of generated frameworks. This proved very difficult to do because SPM doesn't support mixed languages. However, with some focus it shouldn't be too hard to resolve.

Second is to convert all the code to Swift. This seems to be a lot more complicated, but might be a good problem for the future of the library.

Thoughts?

[nickolas-dimitrakas]

@via-guy Thanks for raising this! Can you clarify a bit more about the private Analytics library setup and how it’s referencing the mParticle SDK?

For context, we are in the process of transitioning the SDK over to Swift, though we don’t have a timeline to share just yet. In the meantime, any extra details you can provide about your integration would help us evaluate whether there are workarounds on our side.

[via-guy]

@nickolas-dimitrakas sorry I forgot to close this. I eventually discovered that my SPM setup was broken and I found a better way to do it that fixed the issue.

What didn't work

Originally I wanted to have folder structure:

Analytics
-> AnalyticsModule
--> Classes
---> **/*.swift
-> SPM
--> AnalyticsModule_Location
---> Empty.swift
--> AnalyticsModule_NoLocation
---> Empty.swift

Using this I could define Package.swift:

let package = Package(
    name: "Analytics",
    platforms: [
        .iOS(.v14),
    ],
    products: [
        .library(
            name: "AnalyticsModule",
            targets: [
                "AnalyticsModule",
            ]
        ),
        .library(
            name: "AnalyticsModule_NoLocation",
            targets: [
                "AnalyticsModule_NoLocation",
            ]
        ),
    ],
    dependencies: [
        .package(url: "https://github.com/mParticle/mparticle-apple-sdk.git", .upToNextMajor(from: "8.0.0")),
    ],
    targets: [
        .target(
            name: "AnalyticsModule",
            path: "analytics/AnalyticsModule"
        ),
        .target(
            name: "AnalyticsModule_Location",
            dependencies: [
                .product(name: "mParticle-Apple-SDK", package: "mparticle-apple-sdk"),
            ],
            path: "analytics/SPM/Location"
        ),
        .target(
            name: "AnalyticsModule_NoLocation",
            dependencies: [
                .product(name: "mParticle-Apple-SDK-NoLocation", package: "mparticle-apple-sdk"),
            ],
            path: "analytics/SPM/NoLocation"
        ),
    ]
)

I'd seen a structure like this elsewhere and it worked locally and mostly worked in CI/CD, but for some reason would randomly fail for us.

What worked

Instead of using the SPM folder with the Empty.swift I just created a symlink to AnalyticsModule called AnalyticsModule_NoLocation and then could structure my package:

let package = Package(
    name: "Analytics",
    platforms: [
        .iOS(.v14),
    ],
    products: [
        .library(
            name: "AnalyticsModule",
            targets: [
                "AnalyticsModule",
            ]
        ),
        .library(
            name: "AnalyticsModule_NoLocation",
            targets: [
                "AnalyticsModule_NoLocation",
            ]
        ),
    ],
    dependencies: [
        .package(url: "https://github.com/mParticle/mparticle-apple-sdk.git", .upToNextMajor(from: "8.0.0")),
    ],
    targets: [
        .target(
            name: "AnalyticsModule",
            dependencies: [
                .product(name: "mParticle-Apple-SDK", package: "mparticle-apple-sdk"),
            ],
            path: "analytics/AnalyticsModule"
        ),
        .target(
            name: "AnalyticsModule_NoLocation",
            dependencies: [
                .product(name: "mParticle-Apple-SDK-NoLocation", package: "mparticle-apple-sdk"),
            ],
            path: "analytics/AnalyticsModule_NoLocation"
        ),
    ]
)

In my code I could then use a conditional import to use the correct library and everything worked from there.

#if canImport(mParticle_Apple_SDK_NoLocation)
import mParticle_Apple_SDK_NoLocation
#elseif canImport(mParticle_Apple_SDK)
import mParticle_Apple_SDK
#endif