آموزش استفاده از Retrofit 2 به عنوان REST client

implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'

data class Post(
    val userId: Int,
    val id: Int,
    val title: String,
    val body: String
)

import retrofit2.Call
import retrofit2.http.GET

interface ApiService {

    @GET("posts")
    fun getPosts(): Call<List<Post>>
}

import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory

object RetrofitInstance {

    private const val BASE_URL = "https://jsonplaceholder.typicode.com/"

    val api: ApiService by lazy {
        Retrofit.Builder()
            .baseUrl(BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .build()
            .create(ApiService::class.java)
    }
}

RetrofitInstance.api.getPosts().enqueue(object : Callback<List<Post>> {

    override fun onResponse(
        call: Call<List<Post>>,
        response: Response<List<Post>>
    ) {
        if (response.isSuccessful) {
            val posts = response.body()
            println(posts)
        }
    }

    override fun onFailure(call: Call<List<Post>>, t: Throwable) {
        println("Error: ${t.message}")
    }
})

@GET("posts")
suspend fun getPosts(): List<Post>

lifecycleScope.launch {
    try {
        val posts = RetrofitInstance.api.getPosts()
        println(posts)
    } catch (e: Exception) {
        println("Error: ${e.message}")
    }
}

@POST("posts")
suspend fun createPost(@Body post: Post): Post

val newPost = Post(1, 0, "Title", "Body")

val response = api.createPost(newPost)

val client = OkHttpClient.Builder()
    .addInterceptor { chain ->
        val request = chain.request().newBuilder()
            .addHeader("Authorization", "Bearer token")
            .build()
        chain.proceed(request)
    }
    .build()

if (!response.isSuccessful) {
    println("Error code: ${response.code()}")
}

OkHttpClient.Builder()
    .connectTimeout(30, TimeUnit.SECONDS)