UITabBarItem文字位置适配IOS13解决办法

在ios13之前设置tabbar下部文字位置：

[[UITabBarItem appearance] setTitlePositionAdjustment:UIOffsetMake(0, -5)];

但是在ios13后需要作出判断：

if (@available(iOS 13.0, *)) {

        UITabBarAppearance *appearance = [UITabBarAppearance new];

        appearance.stackedLayoutAppearance.normal.titlePositionAdjustment = UIOffsetMake(0, -5);

        appearance.stackedLayoutAppearance.selected.titlePositionAdjustment = UIOffsetMake(0, -5);

        self.tabBarItem.standardAppearance = appearance;

    }