问NSURLRequest setHTTPBody只读

EN

NSURLRequest *r = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:path]];
[r setHTTPBody:imageData];
r.HTTPBody = imageData;

/*! 
    @method HTTPBody:
    @abstract Sets the request body data of the receiver.
    @discussion This data is sent as the message body of the request, as
    in done in an HTTP POST request.
    @param data the new request body data for the receiver.
*/
@property (copy) NSData *HTTPBody;