How to turn HTTP_POST_RAW_DATA into an image?

I get images from an iOS device, and from what I found out here , I need to look for the original message data using $ HTTP_POST_RAW_DATA or file_get_contents ("PHP: // input");

I can do this, but now I need to know what to do with the raw data as soon as I get it? My structure usually processes images that I uploaded to a temporary folder from a web form ... but this case is different.

How can I download this data?