Yup. Not done off-shore. Just using illegal immigrants. That shouldn't surprise anyone. As a businessman he would make money and cut corners any way he could and he has been proud of that throughout his campaign. I'm sure he will change and be more presidential after elected.
The article linked in submission isn't purely about off-shoring; it compares different level of an AmeriPhone: assembled here, parts from here, and source materials from here, detailing cost and practicality along the way.
I seriously doubt that "assembled in America by illegal immigrants" would be in the spirit of Trump's request of Apple, even though that's how he attained the wealth to put himself in the position to make that request.