Hey all. I am trying to use the <StripeTerminal iO...

# kotlin-native

[Adam Vastopa]

Hey all. I am trying to use the StripeTerminal iOS xcframework in my kmm module. I've manually placed the xcframework in the kmm module in an iOSLibs directory. The klib for the module successfully compiles and I'm able to reference and use the framework in my iOS specific kotlin classes but the build breaks down during the linkDebugTestIos step in the iosTest gradle build task. When I try to specify the framework and framework path in the linkerOpts in my .def file, I get a linking error saying the StripeTerminal framework cannot be found (even though I'm certain it's there - tested by using the absolute path locally for the framework paths).

I've tried specifying the implementation fileTree(dir: <dir>, include: <binary>) in the iosTest { dependencies { ... } } with no luck. Not sure how I can properly link the framework to the test test.

Am I missing something with regards to linking a native iOS framework for use in a KMM module? Any suggestions/ideas are greatly appreciated

[Jeff Lockhart]

I'm not sure specifically for your case, but I do know from my experience a limitation of linker options in the .def file is that the paths can't be relative, which doesn't work for binaries in your repo that need to use a path relative to the project location. I've specified linker options in Gradle instead, in KotlinNativeTarget binary.linkerOpts, to be able to get the absolute path relative to projectDir.

[Adam Vastopa]

Thanks for the message! I tried your suggestion. When my build.gradle looks like the following:

kotlin {
    def iosTarget = kotlin.targets.ios
    def iosDevice = findProperty("kn.ios.platform") == "iphoneos" ?: false
    def target = iosDevice ? "ios-arm64" : "ios-arm64_x86_64-simulator"
    iosTarget.compilations.getByName("main").cinterops.create("StripeTerminal")
    iosTarget.binaries {
        framework("StripeWrapper") {
            linkerOpts += ["-F${projectDir}/iOSLibs/StripeTerminal.xcframework/$target/StripeTerminal.framework"]
            linkerOpts += ["-framework", "StripeTerminal"]
        }
    }
    sourceSets {
        iosTest {
            dependencies {}
        }

I get the error:

Undefined symbols for architecture arm64:
  "_OBJC_CLASS_$_SCPPaymentMethod", referenced from:
      objc-class-ref in result.o
ld: symbol(s) not found for architecture arm64

Execution failed for task ':PointOfSale-StripeWrapper:linkDebugTestIos'.
> Compilation finished with errors

When I add a filepath declaration in the iosTest dependencies like the following:

kotlin {
    def iosTarget = kotlin.targets.ios
    def iosDevice = findProperty("kn.ios.platform") == "iphoneos" ?: false
    def target = iosDevice ? "ios-arm64" : "ios-arm64_x86_64-simulator"
    iosTarget.compilations.getByName("main").cinterops.create("StripeTerminal")
    iosTarget.binaries {
        framework("StripeWrapper") {
            linkerOpts += ["-F${projectDir}/iOSLibs/StripeTerminal.xcframework/$target/StripeTerminal.framework"]
            linkerOpts += ["-framework", "StripeTerminal"]
        }
    }
    sourceSets {
        iosTest {
            dependencies {
                implementation files("${projectDir}/iOSLibs/StripeTerminal.xcframework/$target/StripeTerminal.framework")
            }
        }

I get the error (I verified in my filesystem that the framework is at that exact path):

e: Could not find "/Users/vastopa/src/github.com/Shopify/pos-next-react-native/multiplatform/PointOfSale-StripeWrapper/iOSLibs/StripeTerminal.xcframework/ios-arm64_x86_64-simulator/StripeTerminal.framework" in [/Users/vastopa/src/github.com/Shopify/pos-next-react-native/android, /Users/vastopa/.konan/klib, /Users/vastopa/.konan/kotlin-native-prebuilt-macos-aarch64-1.7.10/klib/common, /Users/vastopa/.konan/kotlin-native-prebuilt-macos-aarch64-1.7.10/klib/platform/ios_simulator_arm64]

Execution failed for task ':PointOfSale-StripeWrapper:compileTestKotlinIos'.
> Compilation finished with errors

[Adam Vastopa]

Seem to be stuck in a circle of either not being able to find the framework or the framework being present but linking doesn't work for whatever reason. Any further suggestions/thoughts?

[Jeff Lockhart]

Be sure to include the -rpath linker option for the runtime path for the dynamic framework.

[Adam Vastopa]

Ah yea, I remember seeing that in a github issue. I tried adding it in in my StripeTerminal.def as linkerOpts = -rpath @loader_path/Frameworks, as well as in

framework("StripeWrapper") {
    linkerOpts += ["-rpath", "@loader_path/Frameworks"]
    linkerOpts += ["-F${projectDir}/iOSLibs/StripeTerminal.xcframework/$target/StripeTerminal.framework"]
    linkerOpts += ["-framework", "StripeTerminal"]
}

Still no luck. Do I need to do something like this comment (although having a hardtime to determine how exactly to fill in the blanks there). One other thing I'm noticing is I can't seem to locate the framework output for StripeWrapper. It should be in build/bin/ios path but I guess it's not there because the linking step fails?

[Jeff Lockhart]

I'm just using the same absolute path as the -F option for -rpath.

[Adam Vastopa]

If I'm understanding correctly, the linkerOpts should look as follows?

iosTarget.binaries {
        framework("StripeWrapper") {
            linkerOpts += ["-rpath", "${projectDir}/iOSLibs/StripeTerminal.xcframework/$target/StripeTerminal.framework"]
            linkerOpts += ["-F${projectDir}/iOSLibs/StripeTerminal.xcframework/$target/StripeTerminal.framework"]
            linkerOpts += ["-framework", "StripeTerminal"]
        }
    }

If so, unfortunately, still seeing the error

Undefined symbols for architecture arm64:
  "_OBJC_CLASS_$_SCPPaymentMethod", referenced from:
      objc-class-ref in result.o
ld: symbol(s) not found for architecture arm64

Execution failed for task ':PointOfSale-StripeWrapper:linkDebugTestIos'.
> Compilation finished with errors

PS - the reason it's that particular class in the error is because I've set up a test to reference the StripeTerminal SDK to test the linking. Without the reference to SCPPaymentMethod, the build/linking passes:

package com.shopify.pos.stripewrapper

import StripeTerminal.SCPPaymentMethod
import kotlinx.coroutines.runBlocking
import kotlin.test.Test
import kotlin.test.assertEquals

class StripePaymentModelsTest {
    @Test
    fun `fake test to testing fixing linking`() = runBlocking {
        val paymentMethod = SCPPaymentMethod()
        assertEquals(paymentMethod, paymentMethod)
    }
}

[Jeff Lockhart]

This is close to what I have, except remove the /StripeTerminal.framework from the end of both paths.

[Adam Vastopa]

Unfortunately, I end up with the same result. Do you know, am I supposed to be seeing a StripeWrapper.framework output in my build products or does the iosTest task only create a .kexe (all I'm seeing is the latter)

[Jeff Lockhart]

No, the test binary doesn't build your library as a .framework. You'll also need to specify the linker options for the test binary:

binaries {
    getTest(DEBUG).linkerOpts(...)
}

[Adam Vastopa]

wow. it worked! thought this day would never come 😅 can't thank you enough for your help!!

[Jeff Lockhart]

Great, glad to help. Linker options can definitely be tricky.

[Adam Vastopa]

it was the framework path excluding the StripeTerminal.framework, the getTest, and the -rpath all combined which I wasn't getting all right in all my testing. happy to be getting more familiar with the intricacies of gradle!

[Jeff Lockhart]

You likely won't want the hard-coded absolute -rpath linker option in the framework build you're distributing, since that path won't exist for consumers of the framework. But it works well for tests.

[Adam Vastopa]

I'm using projectDir, and yea, I only had to add linkerOpts to the test target. thanks for the tip!