SwiftUI Previews Not Working When Using Analytics via SPM

[StarLard]

Step 0: Are you in the right place?

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  file a Github issue.
  • If this is a feature request please use the Feature Request template.
• For general technical questions, post a question on StackOverflow
  with the firebase tag.
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  google group.
• For backend issues, console issues, and other non-SDK help that does not fall under one
  of the above categories, reach out to
  Firebase Support.
• Once you've read this section and determined that your issue is appropriate for
  this repository, please delete this section.

[REQUIRED] Step 1: Describe your environment

• Xcode version: Xcode 12 Beta 6
• Firebase SDK version: 6.31-spm-beta
• Firebase Component: Analytics
• Component version: 6.31-spm-beta
• Installation method: Swift Package Manager

[REQUIRED] Step 2: Describe the problem

Steps to reproduce:

What happened? How can we make the problem occur?

1. Install Firebase Analytics via SPM through a framework which lists it as a dependency.
2. Add -ObjC flag as per instructions.
3. Attempt to view a SwiftUI view in preview.
4. Preview fails to load with error:

Undefined symbols for architecture arm64:
  "_OBJC_CLASS_$_FIRAnalytics", referenced from:
      objc-class-ref in <My framework which depends on Analytics>.o
     (maybe you meant: _OBJC_CLASS_$_FIRAnalyticsConfiguration)
ld: symbol(s) not found for architecture arm64

Building app succeeds, but attempting to run the app will produce the following error:

Could not install at this time.
Failed to load Info.plist from bundle at path /Users/<username>/Library/Developer/CoreSimulator/Devices/B2616B0F-8BB0-4FBC-9A56-D3BD8EEFA502/data/Library/Caches/com.apple.mobile.installd.staging/temp.KrgZu7/extracted/<app name>.app/Frameworks/GoogleAppMeasurement.framework; Extra info about Info.plist: Couldn't stat /Users/<username>/Library/Developer/CoreSimulator/Devices/B2616B0F-8BB0-4FBC-9A56-D3BD8EEFA502/data/Library/Caches/com.apple.mobile.installd.staging/temp.KrgZu7/extracted/<app name>.app/Frameworks/GoogleAppMeasurement.framework/Info.plist: No such file or directory

Adding arm64 to the 'Excluded Architectures' setting as suggested here
will change the previews error to the error produced while attempting to run.

If you have a downloadable sample project that reproduces the bug you're reporting, you will
likely receive a faster response on your issue.

Relevant Code:

Swift package declaration:

let package = Package(
    name: "SomePackage",
    platforms: [ .iOS(.v14), .macOS(.v11), .tvOS(.v14) ],
    products: [
        .library(
            name: "SomePackage",
            targets: ["SomePackage"]),
    ],
    dependencies: [
        .package(name: "Firebase", url: "https://github.com/firebase/firebase-ios-sdk.git", .branch("6.31-spm-beta"))
    ],
    targets: [
        .target(
            name: "SomePackage",
            dependencies: [
                .product(name: "FirebaseAnalytics", package: "Firebase", condition: .when(platforms: [.iOS])),
                .product(name: "FirebaseAuth", package: "Firebase"),
                .product(name: "FirebaseCore", package: "Firebase"),
                .product(name: "FirebaseFirestore", package: "Firebase"),
                .product(name: "FirebaseFirestoreSwift", package: "Firebase"),
            ],
        )
        .testTarget(
            name: "SomePackageTests",
            dependencies: ["SomePackage"]
        ),
    ]
)

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[StarLard]

Possibly related issue? #6360 (comment)

[StarLard]

Tried removing FirebaseAnalytics dependency from my package, but still getting the 'GoogleAppMeasurement can't find plist' error when loading preview even after removing analytics.

[paulb777]

@StarLard Thanks for the report. This looks very similar to #6360 which we haven't been able to reproduce. Are you able to share a reproducible example?

For the most recent comment, it seems that the Xcode project has lingering references to GoogleAppMeasurement. Can you search and remove any of them?

[ryanwilson]

Thanks for the report, I was able to reproduce this one! It works in the simulator but previews are broken, meaning it's different from #6360. Will try with the other package managers as well, but for now here's what I did:

1. Create a blank SwiftUI only iOS project using Xcode 12 b6.
2. Add FirebaseAnalyitcs as a SwiftPM dependency.
3. In ContentView.swift, add import Firebase and replace the contents of body with:

var body: some View {
    Text("Hello, world!")
      .padding()
      // Added this modifier.
      .onAppear {
        Analytics.logEvent("test-event-custom", parameters: nil)
      }
  }

4. Try to regenerate the preview. Build fails:

Undefined symbols for architecture arm64:
  "_OBJC_CLASS_$_FIRAnalytics", referenced from:
      objc-class-ref in ContentView.o

Note: there are multiple warnings above and below that gives us a clue at what's going on, it looks like SwiftPM is looking for the arm64 architecture inside the generated xcframework for the simulator instead of the expected x86_64 slice. At the beginning of the build logs:

'<ObfuscatedLocalProjectPath>/SourcePackages/artifacts/Firebase/FirebaseAnalytics.xcframework' is missing architecture(s) required by this target (arm64), but may still be link-compatible.

Then at the error:

ld: warning: ignoring file <ObfuscatedLocalProjectPath>/Build/Intermediates.noindex/Previews/TestingSwiftPM/Products/Debug-iphonesimulator/FirebaseAnalytics.framework/FirebaseAnalytics, missing required architecture arm64 in file <ObfuscatedLocalProjectPath>/Build/Intermediates.noindex/Previews/TestingSwiftPM/Products/Debug-iphonesimulator/FirebaseAnalytics.framework/FirebaseAnalytics (2 slices)

Looking at the .xcframework contents in the screenshot and Info.plist below, it's looking like the simulator is trying to run an arm64 slice instead of an x86_64 slice for some reason. Perhaps this has to do with changes related to Apple Silicon, or maybe it's just a bug. We'll have to dig into this further.

Info.plist contents:

<key>AvailableLibraries</key>
	<array>
		<dict>
			<key>LibraryIdentifier</key>
			<string>ios-i386_x86_64-simulator</string>
			<key>LibraryPath</key>
			<string>FirebaseAnalytics.framework</string>
			<key>SupportedArchitectures</key>
			<array>
				<string>i386</string>
				<string>x86_64</string>
			</array>
			<key>SupportedPlatform</key>
			<string>ios</string>
			<key>SupportedPlatformVariant</key>
			<string>simulator</string>
		</dict>
		<dict>
			<key>LibraryIdentifier</key>
			<string>ios-arm64_armv7</string>
			<key>LibraryPath</key>
			<string>FirebaseAnalytics.framework</string>
			<key>SupportedArchitectures</key>
			<array>
				<string>arm64</string>
				<string>armv7</string>
			</array>
			<key>SupportedPlatform</key>
			<string>ios</string>
		</dict>
	</array>

[ryanwilson]

As noted in #6375 this happens in Zip file as well, so it must be related to the framework itself and how Xcode tries to run it.

[paulb777]

A workaround is adding arm64 to the Excluded Architectures Build Setting. Thanks to https://developer.apple.com/forums/thread/656509?answerId=627644022#627644022.

[StarLard]

@paulb777 To be clear, adding arm64 is a workaround for the _OBJC_CLASS_$_FIRAnalytics error right? This workaround does not resolve the GoogleAppMeasurement issue for me.

[StarLard]

it seems that the Xcode project has lingering references to GoogleAppMeasurement. Can you search and remove any of them?

Yup, this was the case. I had to completely remove and reinstall Firebase from my project to get it to remove. Clearing package caches did not work.

[kylebrowning]

Adding arm64 to excluded did not work for me. I still receive

[paulb777]

@StarLard @kylebrowning I believe the issue you're discussing is the same as #6360 and should now be resolved with an update. See that issue for details.

I'll close this issue now since the missing symbol issue has a workaround and seems to be a reported Xcode issue.

If you're seeing otherwise, please comment or open a new issue and we'll continue the investigation.

[StarLard]

Hi @paulb777 I've updated to the latest version of the 6.32-spm-beta as per recommendation in #6360 and am still experiencing this issue.

Also while excluding arm64 in my app target is a workaround there, this option is not available within the Swift Package itself so SwiftUI previews are still unavailable there. There's also no way to pass the -ObjC (as far as I'm aware) within a Swift Package outside of passing unsafe flags, but doing so will bar your package from distribution.

[StarLard]

For anyone else experiencing this issue: A workaround to get previews working is to declare a separate package library target that depends on your main target and only import FirebaseAnalytics there; similar the the Firebase package structure itself.