To get started, I'm thinking I need some dependency for the iOS core libraries on networking, e.g. to give me things like URLSessionConfiguration and URLSession. Am I imagining this correctly?

Those aren't third-party dependencies. They're part of the iOS platform

So here's where I'm stuck on my iOS actual implementation:

actual fun getUser(email: String, hostToUse: String): String {

    //<https://stackoverflow.com/questions/3566516/simple-http-post-example-in-objective-c/3566539>
    // <https://blog.jetbrains.com/kotlin/2018/04/kotlinnative-v0-7-released-smoother-interop-frozen-objects-optimisations-and-more/>

    val url = "https://$hostToUse/user/get"
    println("The url is " + url.toString())
    val postString = "data={\"email\":\"$email\"}" as NSString
    println("The postString is " + postString)

    val nsUrl = NSURL.URLWithString(url) as NSURL
    val postData = (postString).dataUsingEncoding(NSUTF8StringEncoding)!!
    val request = NSMutableURLRequest.requestWithURL(nsUrl)
    request.setTimeoutInterval(120.0)
    request.HTTPMethod = "POST"
    request.HTTPBody = postData

    // <https://github.com/ktorio/ktor/blob/master/ktor-client/ktor-client-ios/darwin/src/io/ktor/client/engine/ios/IosClientEngine.kt>
    // <http://hayageek.com/ios-nsurlsession-example/#get-post> //#3.2

    var result : String = "None"
    //val task = session.dataTaskWithRequest(request)
    val task = NSURLSession.sharedSession.dataTaskWithRequest(request) {
            nsData: NSData?, nsURLResponse: NSURLResponse?, nsError: NSError? ->

        if (nsError != null) {
            val message = "The response is: " + nsURLResponse?.description()  + ", error is: " + nsError.description()
            println(message)
        }
        result = nsData.toString()
        println("The data is: " + result)

    }
    task.resume()
    return "The result is: " + result

This compiles when I run a unit test, but it doesn't work as intended. Here's the output:

> Task :ccwsmodule:cleanIosX64Test UP-TO-DATE
> Task :ccwsmodule:compileKotlinIosX64
w: /Users/dana.haukoos/ClearCaptionsGit/KMMApplication/ccwsmodule/src/iosMain/kotlin/com/example/ccwsmodule/CCWSv2.kt: (14, 56): This cast can never succeed
> Task :ccwsmodule:iosX64ProcessResources NO-SOURCE
> Task :ccwsmodule:iosX64MainKlibrary
> Task :ccwsmodule:compileTestKotlinIosX64
> Task :ccwsmodule:linkDebugTestIosX64
> Task :ccwsmodule:iosX64Test
2020-10-26 23:22:51.814 simctl[18263:5286149] Unable to locate a bundle at URL file:///Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/DeviceTypes/iPhone%2012%20Pro%20Max.simdevicetype/
2020-10-26 23:22:51.814 simctl[18263:5286149] Unable to locate a bundle at URL file:///Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/
The url is <https://our.domain.com/user/get>
The postString is data={"email":"<mailto:dana.haukoos@clearcaptions.com|dana.haukoos@clearcaptions.com>"}
The response is The result is: None
BUILD SUCCESSFUL in 31s
5 actionable tasks: 4 executed, 1 up-to-date
11:22:52 PM: Tasks execution finished 'cleanIosX64Test iosX64Test --tests "com.example.ccwsmodule.ExampleUnitTest.test_getUser"'

I've noticed the warning:

w: /Users/dana.haukoos/ClearCaptionsGit/KMMApplication/ccwsmodule/src/iosMain/kotlin/com/example/ccwsmodule/CCWSv2.kt: (14, 56): This cast can never succeed

but haven't figured out how to resolve it, and I'm not clear on it's impact. Obviously, none of the println statements in task callback are run - I'm not clear on how the async aspect is supposed to work.

Since we see “The response is The result is: None” in the logs, I think you are hitting the callback but not getting data. Is the url correct? Does the same request work in an external tool like Postman? Does the equivalent code work if you write the same request in Swift?

The reason I think the callback isn't working is that I never see the output from the line

println("The data is: " + result)

not 100% sure on that though

(I tried adding an NSThread.sleep() to test that idea, but it created other issues, so I bailed on that exploration.)

Does my statement about the println("Hello world") test make sense?

And now I’m seeing that yeah, your result string is never updating. You initialize it to “none” and that’s what prints

On the Swift comparison side, I've tried that with different, yet not successful results. (The irony is I grabbed code out of our working application. I'm using a Swift playground as my testbed, so I'm not sure if that's part of my problem somehow...) Here's that code: var request = URLRequest(url: URL(string: "https://\(hostToUse)/user/get")!) request.setValue("close", forHTTPHeaderField: "Connection") request.httpMethod = "POST" request.timeoutInterval = 120.0 let postString = "data={\"email\":\"\(email)\"}" print("**Service Post : GetUser** =\(postString)") request.httpBody = postString.data(using: .utf8) let task = URLSession.shared.dataTask(with: request) { data, response, error in   guard let data = data, error == nil else {     print("errorInGetUser=\(String(describing: error))")     print("postString=\(postString)")     //completion(false, nil )     return   }   if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {     print("statusCode should be 200, but is (httpStatus.statusCode)")     //print("response = \(response)")   }   if let body_response = String(data: data, encoding: String.Encoding.utf8) {     print(body_response)   } } task.resume() At least I'm getting an error, but I haven't figured out the root issue: errorInGetUser=Optional(Error Domain=NSURLErrorDomain Code=-1003 "A server with the specified hostname could not be found." UserInfo={NSUnderlyingError=0x600000645950 {Error Domain=kCFErrorDomainCFNetwork Code=-1003 "(null)" UserInfo={_kCFStreamErrorCodeKey=8, _kCFStreamErrorDomainKey=12}}, NSErrorFailingURLStringKey=https://our.domain.com/user/get, NSErrorFailingURLKey=https://our.domain.com/user/get, _kCFStreamErrorDomainKey=12, _kCFStreamErrorCodeKey=8, NSLocalizedDescription=A server with the specified hostname could not be found.})\n"

Googling on the error message Error Domain=NSURLErrorDomain Code=-1003 "A server with the specified hostname could not be found." did not lead me to any resolution.

Do you think running this code in a Swift playground is somehow possibly related to why I'm getting this error?

Well, I found I had a typo in the URL for my test case in Swift, so that's working now, at least.

Unfortunately, it doesn't add any insight to my KMM iOS issue, but it's still helpful to know that is working now.

It occurs to me that I have no evidence that the server is even getting the http call...

I like your suggestion of trying this. Any further ideas what to look into on my issue building this module?

sorry about that

When I try to run the function from the Kotlin app, the app crashes. When trying the iOS version of the app, I get Uncaught Kotlin exception: kotlin.native.IncorrectDereferenceException: illegal attempt to access non-shared com.example.ccwsmodule.CCWSv2.$getUser$lambda-0$FUNCTION_REFERENCE$0@20cca48 from other thread. Googling that tells me I have an issues with async thread management, but not sure the best way to deal with it. For what it's worth, here's how I'm calling the function in the main app at the moment:

println("getUser is ${ccws.getUser(email, host)}")

When I next run the Android version of the app, I get: E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.kmmapplication.androidApp, PID: 4481 java.lang.NoSuchFieldError: No static field INSTANCE of type Lorg/apache/http/conn/ssl/AllowAllHostnameVerifier; in class Lorg/apache/http/conn/ssl/AllowAllHostnameVerifier; or its superclasses (declaration of 'org.apache.http.conn.ssl.AllowAllHostnameVerifier' appears in /system/framework/framework.jar!classes3.dex) at org.apache.http.conn.ssl.SSLConnectionSocketFactory.<clinit>(SSLConnectionSocketFactory.java:151) at org.apache.http.impl.client.HttpClientBuilder.build(HttpClientBuilder.java:977) at org.apache.http.impl.client.HttpClients.createDefault(HttpClients.java:56) at com.example.ccwsmodule.CCWSv2.getUser(CCWSv2.kt:19) ...

For the iOS issue, I guess the NSURLSession is crossing thread boundaries which means the completion handler lambda has to be frozen. And that means you can't have a mutable var for your result field. Try something like this

val result = AtomicReference("None")
val completionHandler = { nsData: NSData?, nsURLResponse: NSURLResponse?, nsError: NSError? ->
    if (nsError != null) {
        val message =
            "The response is: " + nsURLResponse?.description() + ", error is: " + nsError.description()
        println(message)
    }
    result.value = nsData?.bytes?.reinterpret<ByteVar>()?.toKString() ?: ""
    println("The data is: " + result.value)
}.freeze()
val task =
    NSURLSession.sharedSession.dataTaskWithRequest(request, completionHandler)
task.resume()
return "The result is: " + result.value

(A clean & build didn't resolve it)

Android issue sounds weird. AFAIK nothing should be accessing org.apache.http unless you set it up that way intentionally or are using a very very old device.

I thought you had that working previously though

So I have no theory as to why the unit test succeeds, but the app that calls it dies inside the function.

The good news is that's definitely just an Android-side issue so it should be solvable regardless of your KMM setup

in that case I'd generally advise not using the apache client. Look at okhttp instead for Android web calls

So not having any success with the okhttp version. The app doesn't crash, but it returns "Exception is null" for this code:

actual fun getUser(email: String, hostToUse: String): String {
        val client = OkHttpClient()

        val url = "https://$hostToUse/user/get"
        println("The url is " + url.toString())
        val postString = "data={\"email\":\"$email\"}"
        println("The postString is " + postString)

       // val body: RequestBody = create(json, JSON)

        val body: RequestBody = RequestBody.create(
           //MediaType.parse("application/json"), postString
            MediaType.parse("application/x-www-form-urlencoded; charset=UTF-8"), postString
        )
        val request: Request = Request.Builder()
            .url(url)
            .post(body)
            .build()

        val call: Call = client.newCall(request)
        return try {
            val response: Response = call.execute()
            response.body().toString()
        } catch (e: Exception) {
            "Exception is " + e.message
        }
    }
}

Ok, here's an Android version using okhttp that works in the unit test:

actual fun getUser(email: String, hostToUse: String): String {
    //val client = OkHttpClient()

    val CLIENT_TIMEOUT_MILLIS: Long = 60000
    val client  = OkHttpClient.Builder()
        .connectTimeout(CLIENT_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)
        .writeTimeout(CLIENT_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)
        .readTimeout(CLIENT_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)
        .build()

    val url = "https://$hostToUse/user/get"
    println("The url is " + url.toString())
    val postString = "data={\"email\":\"$email\"}"
    println("The postString is " + postString)

   // val body: RequestBody = create(json, JSON)

    val body: RequestBody = RequestBody.create(
        //MediaType.parse("application/json"), postString
        MediaType.parse("application/x-www-form-urlencoded; charset=UTF-8"), postString
    )
    val request: Request = Request.Builder()
        .url(url)
        .post(body)
        .build()
    println("The request body is " + request.body())

    val call: Call = client.newCall(request)
    return try {
        val httpResponse: Response = call.execute()
        println("POST Response Status: " + httpResponse.code())
        println("POST Response Success: " + httpResponse.isSuccessful)
        println("POST Response contentLegnth: " + httpResponse.body()!!.contentLength())

        val reader = BufferedReader(
            InputStreamReader(
                httpResponse.body()!!.byteStream()
            )
        )
        var inputLine: String?
        val response = StringBuffer()
        while (reader.readLine().also { inputLine = it } != null) {
            response.append(inputLine)
        }
        reader.close()

        response.toString()
    } catch (e: Exception) {
        "Exception is " + e.message
    }
}

Still need to get it working when called via the app.

Here's a different question I have about my kmm module. I see the Android aar file in mymodule/build/outputs/aar/mymodule-debug.aar. But I don't see where to find the corresponding iOS build artifact?

The iOS artifact will depend on your gradle setup. By default it will create a klib file which can be consumed by other kotlin projects. Probably you have some config based on the template you used that will also generate a framework.

Take a look inside

build/bin

in your shared module

try a

./gradlew build

to build everything and probably there will be a framework in there too

Task androidApplint

Ran lint on variant debug: 6 issues found Ran lint on variant release: 4 issues found Wrote HTML report to file:///Users/dana.haukoos/ClearCaptionsGit/KMMApplication/androidApp/build/reports/lint-results.html Wrote XML report to file:///Users/dana.haukoos/ClearCaptionsGit/KMMApplication/androidApp/build/reports/lint-results.xml Expiring Daemon because JVM heap space is exhausted Daemon will be stopped at the end of the build after running out of JVM memory Expiring Daemon because JVM heap space is exhausted Expiring Daemon because JVM heap space is exhausted Expiring Daemon because JVM heap space is exhausted Expiring Daemon because JVM heap space is exhausted Expiring Daemon because JVM heap space is exhausted Expiring Daemon because JVM heap space is exhausted

Task ccwsmodulelinkDebugTestIosX64 FAILED

e: /Users/dana.haukoos/ClearCaptionsGit/KMMApplication/ccwsmodule/src/iosTest/kotlin/com/example/ccwsmodule/iosTest.kt: Test function must return Unit: com.example.ccwsmodule.iOSUnitTest.test_getUser FAILURE: Build failed with an exception. * What went wrong: Execution failed for task 'ccwsmodulelinkDebugTestIosX64'.

Compilation finished with errors

* Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights. * Get more help at https://help.gradle.org BUILD FAILED in 1m 54s 206 actionable tasks: 2 executed, 204 up-to-date Expiring Daemon because JVM heap space is exhausted

though, it probably got far enough to build the framework anyway if you're just looking for that

(Also seeing if I've fixed the unit test.)

OK, so here's where I'm at: So on the iOS side, my function works in the iOS app, but not in the unit test. Conversely, on the Android side, my function works in the unit test, but not in the Android app. (To clarify, when I say it works, I mean I see the expected response data in my println() statements embedded in the function.)

Earlier we speculated that the iOS unit test didn't work due to the test ending before the function returned its data. Do you know of a simple async test example to test this hypothesis?