去掉导航条线

- (UIImageView *)findHairlineImageViewUnder:(UIView *)view{    if ([view isKindOfClass:UIImageView.class] && view.bounds.size.height <= 1.0)    {        return (UIImageView *)view;    }    for (UIView *subview in view.subviews)    {        UIImageView *imageView = [self findHairlineImageViewUnder:subview];        if (imageView)        {            return imageView;        }    }    return nil;}

UIImageView *imageView = [self findHairlineImageViewUnder:self.navigationBar];    imageView.hidden = YES;