Reskit patchObject - 在php服务器端提取对象

I'm trying to handle ios reskit 2.x request on php I send the request this way

[objectManager putObject:obj path:url parameters:params..

I do find the parameters I sent in params by checking

file_get_contents('php://input')

But where can't I find the "obj" - the object that I'm trying to update (Same thing happens with patchObject)

Thanks.

RKObjectRequestOperation was missing