如何使用gziped内容发送HTTP POST请求？

I'm developing iPhone app and manually constructing POST requests. Currently, need to compress JSON data before sending it, so looking how to tell a server the content is compressed. Setting content type header to gzip might be not acceptable because server expects JSON data. I'm looking for transparent solution, something like just to add some header telling JSON data is compressed into gzip.I'm developing iPhone app and manually construc