Upload with Kotlin Native

kotlin_native_upload.kt

sealed class UploadFileType

data class UploadFileForm(
    val key: String,
    val value: String,
    val filename: String = "file.jpg",
    val contentType: String = "image/jpeg"
) : UploadFileType()

data class UploadForm(
    val key: String,
    val value: String
) : UploadFileType()

fun multipartUpload(postUrl: String, bodies: ArrayList<UploadFileType>, headers: ArrayList<Pair<String, String>>?): String {

    val request = NSMutableURLRequest(NSURL.URLWithString(postUrl)!!)
    request.setHTTPMethod("POST")
    val boundary = "---------------------------14737809831466499882746641449"
    val contentType = "multipart/form-data; boundary=$boundary"
    request.addValue(contentType, "Content-Type")
    headers?.forEach {
        request.addValue(it.second, it.first)
    }

    val postBody: NSMutableData = NSMutableData.data() as NSMutableData
    val boundaryStr = "\r\n--$boundary\r\n" as NSString

    bodies.forEach {
        postBody.appendData(boundaryStr.dataUsingEncoding(NSUTF8StringEncoding)!!)
        when (it) {
            is UploadFileForm -> {
                val nsdata = NSData.create(contentsOfFile = it.fileUrl) ?: throw Exception("file not found!")
                val filestr = "Content-Disposition: form-data; name=\"${it.fileKey}\"; filename=\"${it.filename}\"\r\n" as NSString
                val constr = "Content-Type: ${it.contentType}\r\n\r\n" as NSString

                postBody.appendData(filestr.dataUsingEncoding(NSUTF8StringEncoding)!!)
                postBody.appendData(constr.dataUsingEncoding(NSUTF8StringEncoding)!!)
                postBody.appendData(NSData.dataWithData(nsdata))
            }
            is UploadForm -> {
                val formStr = "Content-Disposition:form-data; name=\"${it.key}\"\r\n\r\n" as NSString
                val sfStr = it.value as NSString
                postBody.appendData(formStr.dataUsingEncoding(NSUTF8StringEncoding)!!)
                postBody.appendData(sfStr.dataUsingEncoding(NSUTF8StringEncoding)!!)
            }
        }
    }
    val endstr = "\r\n--$boundary--\r\n" as NSString
    postBody.appendData(endstr.dataUsingEncoding(NSUTF8StringEncoding)!!)
    println("length ${postBody.length}")
    request.setHTTPBody(postBody)

    val data = NSURLConnection.sendSynchronousRequest(request, null, null)
    val responseString = NSString.stringWithUTF8String(data!!.bytes!!.reinterpret())
    return responseString ?: "None"
}