A modern programming language that makes developers happier.

kotlinlang

Anyone have a project using Apple's Compression framework, or for that matter any Apple framework that isn't "platform.Foundation"?  I'm specifically looking for how to add a dependency on an Apple framework so that an `import platform.Compression` statement can work, not a third-party cocoapod, so I can import it and use it in KMP code. I'm still searching around but so far not having much luck.  Thanks in advance for any info...

Hi again :slightly_smiling_face:

What a coincidence, I'm trying to figure out the exact same thing.

I basically want to write lines to a gzip compressed file.

The JVM/Android code looks like this:

```actual class CompressedLineWriter actual constructor(filePath: String) {
    private val writer = PrintWriter(GZIPOutputStream(File(filePath).outputStream()))

    actual fun writeLine(line: String) {
        writer.println(line)
    }

    actual fun close() {
        writer.close()
    }
}```
I guess on iOS I could achieve the same thing with the Compression Framework [1]. But just like you I am unable to access it with Kotlin.
One reason for this could be that it might be a Swift-only framework, but Kotlin only supports Objective-C frameworks.

I might be able to implement my use case with `platform.zlib`, but that will involve a lot of pointer handling and manual memory management that I'm really not looking forward to.


[1] <https://developer.apple.com/documentation/accelerate/compressing_and_decompressing_files_with_swift_stream_compression>

I'm looking at doc for Compression and it has an objective C API so the lib is somewhere in the Apple SDK. Rummaging in `.konan/kotlin-native-prebuilt-windows-x86_64-1.6.10\konan\platformDef\ios_arm64` there are a bunch of .def files but Compression isn't one of them. So now I'm looking in the Apple SDK to find if there is a libcompression file someplace - search hits have shown references to this but I haven't found it yet. If I can find that and the associated headers I can do my own cinterop setup.  Also have a "wild hare" chase :slightly_smiling_face: in mind, considering porting pieces of jzlib project (java ZLib) to KMP, will see where that goes.  Also in case its useful, if you haven't already check out <https://github.com/korlibs/korio>, they have a KMP port of compression too. Their Zip file support is insufficient for me, and their port of Compression uses a lot of other stuff in their library, and I haven't used it so don't know how good it is, but its there :slightly_smiling_face:

Thanks <@U016CJFP8LX>, I’ll have a look.

Not sure if it helps but I have found some symbols from the compression framework in  `platform.darwin`, for example `import platform.darwin.compression_stream_process`  and a bunch of other symbols which are available since iOS 9.0.

Everything available since iOS 13 (like `OutputFilter`) however is missing. Maybe those are Swift-specific :blob-shrug:

Thanks for finding the darwin stuff, I didn't even know to look in there. I'm gonna try it out...