swift项目中，在tabbarviewcontroller文件里添加一个uinavigantioncontroller，tabbarviewcontroller的父类是UITabBarController；当点击不同的item时，实现未选中图片与选中图片的切换、未选中时与选中时的tab文字颜色更换，且能跳转到不同的viewcontroller文件，现在有5个viewcontroller，分别是X、Y、Z、M、N

你可以在tabbarviewcontroller的viewDidLoad方法中添加以下代码来实现：

// 创建5个视图控制器
let xVC = XViewController()
let yVC = YViewController()
let zVC = ZViewController()
let mVC = MViewController()
let nVC = NViewController()

// 创建5个导航控制器，并将对应的视图控制器设置为根视图控制器
let xNav = UINavigationController(rootViewController: xVC)
let yNav = UINavigationController(rootViewController: yVC)
let zNav = UINavigationController(rootViewController: zVC)
let mNav = UINavigationController(rootViewController: mVC)
let nNav = UINavigationController(rootViewController: nVC)

// 设置未选中图片与选中图片
xNav.tabBarItem = UITabBarItem(title: "X", image: UIImage(named: "unselectedImage"), selectedImage: UIImage(named: "selectedImage"))
yNav.tabBarItem = UITabBarItem(title: "Y", image: UIImage(named: "unselectedImage"), selectedImage: UIImage(named: "selectedImage"))
zNav.tabBarItem = UITabBarItem(title: "Z", image: UIImage(named: "unselectedImage"), selectedImage: UIImage(named: "selectedImage"))
mNav.tabBarItem = UITabBarItem(title: "M", image: UIImage(named: "unselectedImage"), selectedImage: UIImage(named: "selectedImage"))
nNav.tabBarItem = UITabBarItem(title: "N", image: UIImage(named: "unselectedImage"), selectedImage: UIImage(named: "selectedImage"))

// 设置未选中时与选中时的tab文字颜色更换
UITabBarItem.appearance().setTitleTextAttributes([NSAttributedString.Key.foregroundColor: UIColor.gray], for: .normal)
UITabBarItem.appearance().setTitleTextAttributes([NSAttributedString.Key.foregroundColor: UIColor.blue], for: .selected)

// 将5个导航控制器添加到tabbarviewcontroller中
self.viewControllers = [xNav, yNav, zNav, mNav, nNav]

这样就可以实现在tabbarviewcontroller文件里添加一个uinavigantioncontroller，点击不同的item时，实现未选中图片与选中图片的切换、未选中时与选中时的tab文字颜色更换，且能跳转到不同的viewcontroller文件。