presentModalViewController方法，present一个透明的viewController,带动画效果

//假设需要被present的控制器实例为controller
 UIViewController * rootcontroller = self.view.window.rootViewController;
 rootcontroller.modalPresentationStyle = UIModalPresentationCurrentContext;//进入的动画失效

 [rootcontroller presentViewController:controller animated:NO completion:^{
     rootcontroller.modalPresentationStyle = UIModalPresentationFullScreen;
  }];
 controller.view.transform = CGAffineTransformMakeTranslation(0, controller.view.frame.size.height);
 [UIView animateWithDuration:0.35 animations:^{
     controller.view.transform = CGAffineTransformMakeTranslation(0, 0);
 }];