How to use the HttpClient class in Visual C++ 2017

uwp_HttpClient.cpp

void cpp_uwp::json_test::Button_Click_1(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
{
	using namespace Windows::Web::Http;
	using namespace Windows::Storage::Streams;
	ActivityIndicator1->IsActive = true;
	IHttpClient^ NetHttp1 = ref new HttpClient();

	concurrency::create_task(NetHttp1->GetAsync(ref new Uri("https://うあーるえる"))).then([this](IHttpResponseMessage^ res) {
		concurrency::create_task(res->Content->ReadAsBufferAsync()).then([this](IBuffer^ buf) {
			std::function<Platform::String ^ (std::string)> Utf8ToPlatformString{ [](std::string stin) {
				std::wstring_convert<std::codecvt_utf8_utf16<wchar_t> > converter;
				return ref new Platform::String(converter.from_bytes(stin.c_str()).c_str());
			} };

			DataReader^ BufRead = DataReader::FromBuffer(buf);
			Platform::Array<unsigned char>^ arr_stream = ref new Platform::Array<unsigned char>(buf->Length);
			BufRead->ReadBytes(arr_stream);
			std::stringstream ss1;
			for (int i = 0; i < buf->Length; ++i)
			{
				ss1 << static_cast<char>(arr_stream[i]);
			}
			Edit1->Text = Utf8ToPlatformString(ss1.str());
			ActivityIndicator1->IsActive = false;
		});
	});
}