CATransition* transition = [CATransition animation];

transition.type = kCATransitionPush;        //动画效果

transition.subtype = kCATransitionFromLeft;  //动画方向

[nav.visibleViewController.navigationController.view.layer addAnimation:transition forKey:kCATransition];

[nav.visibleViewController.navigationController pushViewController:vc animated:NO];

　　// 放在跳转的地方  只生效一次