如何将Platform :: String ^放入Windows :: Storage :: Streams :: Buffer？

Question

Platform::String^ m_json = L"{ \"Mode\": \"DeleteAllHumans\"}";

稍后我想使用以下函数上传该字符串：

IAsyncOperation UploadBlobAsync(Windows::Storage::Streams::IBuffer jsonBlob, unsigned int bufferSize);

我无法使用Windows.Security.Cryptography.CryptographicBuffer。