想要将视图控制器添加到选项卡项

Question

您好，我目前正在一个项目中，该项目需要两个选项卡栏，一个在顶部，第二个在底部，我添加了这些选项卡栏，但是问题是我被困在使用这些选项卡栏项在视图控制器之间导航。使用标签栏

let tabbar1 = UITabBar() //Note that tabbar height is fixed to 49
view.addSubview(tabbar1)

tabbar1.translatesAutoresizingMaskIntoConstraints = false
tabbar1.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 0.0).isActive = true
tabbar1.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: 0.0).isActive = true
tabbar1.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 0.0).isActive = true

let contacts = UITabBarItem(tabBarSystemItem: UITabBarItem.SystemItem.contacts, tag: 100)
let bookmarks = UITabBarItem(tabBarSystemItem: UITabBarItem.SystemItem.bookmarks, tag: 101)
tabbar1.setItems([contacts, bookmarks], animated: false)

let tabbar2 = UITabBar() //Note that tabbar height is fixed to 49
view.addSubview(tabbar2)

tabbar2.translatesAutoresizingMaskIntoConstraints = false
tabbar2.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 0.0).isActive = true
tabbar2.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: 0.0).isActive = true
tabbar2.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: 0.0).isActive = true

let downloads = UITabBarItem(tabBarSystemItem: UITabBarItem.SystemItem.downloads, tag: 103)
let favorites = UITabBarItem(tabBarSystemItem: UITabBarItem.SystemItem.favorites, tag: 104)
tabbar2.setItems([downloads, favorites], animated: false)