使用 Kotlin Native 开发跨平台 Library

class Greeting {
    fun greeting(): String {
        return "Hello, ${Platform().platform}!"
    }
}

import platform.UIKit.UIDevice

actual class Platform actual constructor() {
    actual val platform: String = UIDevice.currentDevice.systemName() + " " + UIDevice.currentDevice.systemVersion
}

// 配置 serialization plugin
// https://ktor.io/docs/json.html#kotlinx_dependency
// https://github.com/Kotlin/kotlinx.serialization#setup
// https://kotlinlang.org/docs/mpp-discover-project.html#multiplatform-plugin
plugins {
    kotlin("plugin.serialization") version "1.5.10"
}

kotlin {
  // 配置 target
  // https://kotlinlang.org/docs/mpp-discover-project.html#targets
  val macos = macosX64("macos")
  val ios = iosX64("ios")
  val iosArm64 = iosArm64("iosArm64")
  
  // https://kotlinlang.org/docs/mpp-discover-project.html#source-sets
  sourceSets {
    val commonMain by getting {
                dependencies {
                // 添加 ktor core 到 common
                // https://ktor.io/docs/http-client-multiplatform.html#add-dependencies
                // https://kotlinlang.org/docs/mpp-add-dependencies.html
                    implementation("io.ktor:ktor-client-core:$ktorVersion")
                    implementation("io.ktor:ktor-client-serialization:$ktorVersion")
                }
            }
            
    val iosMain by getting {
        dependsOn(commonMain)
        dependencies {
            // 添加 ktor for ios
            implementation("io.ktor:ktor-client-ios:$ktorVersion")
        }
    }

    val macosMain by getting {
        dependsOn(commonMain)
        dependencies {
            // 添加 ktor for macOS
            implementation("io.ktor:ktor-client-curl:$ktorVersion")
        }
    }

    // 配置每个 target 编译出来的 Framework 名称
    // https://kotlinlang.org/docs/mpp-build-native-binaries.html#declare-binaries
    configure(listOf(ios, iosArm64, macos)) {
        // listOf(RELEASE) 是指 Build 时只编译 Release 版本
        binaries.framework(listOf(RELEASE)) {
            baseName = "HappyNasa"
        }
    }
  }
}

@Serializable
@SerialName("APOD")
data class APOD(val date: String,
                val explanation: String,
                val hdurl: String,
                val media_type: String,
                val service_version: String,
                val title: String,
                val url: String)

class NASA(private val apiKey: String) {

    val NASAEntryPoint.fullPath: String
        get() {
            return nasaBaseURL + this.path
        }

    private val client = HttpClient() {
        install(JsonFeature) {
            serializer = KotlinxSerializer()
        }
    }

    private val nasaBaseURL: String = "https://api.nasa.gov"

    enum class NASAEntryPoint(val path: String) {
        APOD( "/planetary/apod")

    }

    suspend fun getAPOD(): APOD? {
        val response: HttpResponse =  client.get(NASAEntryPoint.APOD.fullPath) {
            parameter("api_key", apiKey)
        }

        return try {
            val apod: APOD = response.receive()
            apod
        } catch (e: NoTransformationFoundException) {
            null
        }
    }
}

import PackageDescription

let package = Package(
    name: "kotlin_demo_lib",
    products: [
        .library(
            name: "kotlin_demo_lib",
            targets: ["kotlin_demo_lib", "HappyNasa"]),
    ],
    targets: [
        .target(
            name: "kotlin_demo_lib",
            dependencies: []),
        .binaryTarget(
                    name: "HappyNasa",
                    path: "Sources/happy_lib.xcframework"),
        .testTarget(
            name: "kotlin_demo_libTests",
            dependencies: ["kotlin_demo_lib"]),
    ]
)

import UIKit
import kotlin_demo_lib
import HappyNasa

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let a = Greeting().greeting()
        print(a)

        let nasaClient = NASA.init(apiKey: "{API_KEY}")
        nasaClient.getAPOD { apod, error in
            if let apod = apod {
                print(apod.title)
            } else {
                print("Get apod failed")
            }
        }
    }
}