Final code snippet for cache-enabled Retrofit

RetrofitAPI.kt

val cacheSize = (5 x 1024 x 1024).toLong()
val myCache = Cache(context.cacheDir, cacheSize)

val okHttpClient = OkHttpClient.Builder()
                .cache(myCache)
                .addInterceptor { chain ->
                    var request = chain.request()
                    request = if (hasNetwork(context)!!)
                        request.newBuilder().header("Cache-Control", "public, max-age=" + 5).build()
                    else
                        request.newBuilder().header("Cache-Control", "public, only-if-cached, max-stale=" + 60 * 60 * 24 * 7).build()
                    chain.proceed(request)
                }
                .build()

val retrofit = Retrofit.Builder()
                .baseUrl(BASE_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .client(okHttpClient)
                .build()