This article shows how to rotate pdf pages:

Remember that to use the following method you need a Premium license.

First you should create and open a PDFDoc instance:

PDFDoc *m_doc = [[PDFDoc alloc] init];
[m_doc open:path :pwd];

Then you can use setPageRotate method to rotate some or all pages (use iteration to rotate all pages):

/**
* @param pageno 0 based page NO.
* @param degree rotate angle in degree, must be 90 * n.
* @return true or false
*/
[m_doc setPageRotate:0 :90];