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,controller的背景色设置为clearColor
 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);
 }];

 将其封装成Catrgory后，备用：

- (void) presentTransparentController:(UIViewController *)controller withDuration:(CGFloat) duration {
    
    controller.view.backgroundColor = [UIColor clearColor];
    controller.view.transform = CGAffineTransformMakeTranslation(0, controller.view.frame.size.height);
    [UIView animateWithDuration:duration animations:^{
        controller.view.transform = CGAffineTransformMakeTranslation(0, 0);
    }];
    
    self.modalPresentationStyle = UIModalPresentationCurrentContext;//让进入的动画失效
    [self presentViewController:controller animated:NO completion:^{
        self.modalPresentationStyle = UIModalPresentationFullScreen;
    }];
}