iOS12 lt_setBackgroundColor can't set navigationBar Color?

[miniLV]

[self.navigationController.navigationBar lt_setBackgroundColor:[color orangeColor]];
in iOS12 will display clearColor

[miniLV]

    if (iOS12) {
       //显示正常颜色
        self.navigationController.navigationBar.barTintColor = ACG_ThemeColor;
        //显示透明颜色
        [self.navigationController.navigationBar lt_setBackgroundColor:ACG_ThemeColor];
    }