iOS 导航栏消失

iOS15 导航栏在静止时，设置的图片会透明，以及消失。

解决如下

 if (@available(iOS 13.0, *)) {
                UINavigationBarAppearance *appearance = [UINavigationBarAppearance new];
                UIImage *backGroundImage = [UIImage imageNamed:@"home_nav_imgV"];
                backGroundImage = [backGroundImage resizableImageWithCapInsets:UIEdgeInsetsZero resizingMode:UIImageResizingModeStretch];
                appearance.backgroundImage = backGroundImage;
                appearance.shadowColor = [UIColor clearColor];
                appearance.shadowImage = [UIImage new];
                self.navigationController.navigationBar.standardAppearance = appearance;
                self.navigationController.navigationBar.scrollEdgeAppearance = self.navigationController.navigationBar.standardAppearance;
            } else {
                UIImage *backGroundImage = [UIImage imageNamed:@"home_nav_imgV"];
                backGroundImage = [backGroundImage resizableImageWithCapInsets:UIEdgeInsetsZero resizingMode:UIImageResizingModeStretch];
                [self.navigationController.navigationBar setBackgroundImage:backGroundImage forBarPosition:UIBarPositionAny barMetrics:UIBarMetricsDefault];
                [self.navigationController.navigationBar setShadowImage:[UIImage new]];
            }