[objc] UIBarButtonItem, 회전

CGAffineTransform myTransform = CGAffineTransformMakeRotation(
M_PI);

UIBarButtonItem * currentItem =  self.navigationItem.leftBarButtonItem;

currentItem.customView.transform = myTransform;

self.navigationItem.leftBarButtonItem.customView.layer.anchorPoint = CGPointMake(0.6, 0.7);

//anchorPoint 회전축. 0.5 0.5가 초기치인듯.