Why not move elsewhere? The only factories able to produce the required volumes are, by virtue of great planning by China, there, and perform work on a contract basis for many companies, Apple included, Dell, and so on.
EDIT: Since you edited your comment instead of responding to mine, yes China is the only country that can currently support Apple's manufacturing needs. But if Apple actually felt it was unethical to work with China for whatever reason they could begin the process to have factories set up elsewhere, even in the United States or Mexico, within a few years. It would obviously impact their profit margins, but you are arguing that ethics is a "huge priority" while providing nothing substantive to back up that claim.
I take a nuanced view of these things. I understand that in vast swathes of rural China job opportunities like this were until recently the only way to make a decent living for many people (most of my family is Asian, and I have investments there). And I also know that most companies could not in fact replicate that technology.
But Apple is rubbing everyone’s nose in their social virtue. If they really believed what they were saying they could definitely replicate a factory like Foxconn’s in Texas for, say, $100 billion. Dell couldn’t, HP probably couldn’t, but they aren’t telling me how to live my life either.