五种 自定义tabbar导航demo

自定义TabBar导航通常涉及到底部或顶部的一组按钮，用于在不同的视图控制器之间切换。以下是一个简单的自定义TabBar导航的实现示例：

import UIKit
 
class CustomTabBarController: UIViewController {
 
    override func viewDidLoad() {
        super.viewDidLoad()
        setupTabBar()
    }
 
    func setupTabBar() {
        let firstViewController = UIViewController()
        firstViewController.view.backgroundColor = .red
        let secondViewController = UIViewController()
        secondViewController.view.backgroundColor = .green
        
        addChild(firstViewController)
        addChild(secondViewController)
        
        view.addSubview(firstViewController.view)
        view.addSubview(secondViewController.view)
        
        firstViewController.view.translatesAutoresizingMaskIntoConstraints = false
        secondViewController.view.translatesAutoresizingMaskIntoConstraints = false
        
        NSLayoutConstraint.activate([
            firstViewController.view.topAnchor.constraint(equalTo: view.topAnchor),
            firstViewController.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            firstViewController.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            firstViewController.view.bottomAnchor.constraint(equalTo: view.centerYAnchor),
            
            secondViewController.view.topAnchor.constraint(equalTo: view.centerYAnchor),
            secondViewController.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            secondViewController.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            secondViewController.view.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])
        
        // 可以添加更多的视图控制器和相应的约束
    }
}
 
// 在AppDelegate中设置window的rootViewController
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // 创建一个自定义的TabBarController
    window?.rootViewController = CustomTabBarController()
    window?.makeKeyAndVisible()
    return true
}

这个示例展示了如何创建一个自定义的TabBarController，它有两个子视图控制器，每个视图控制器占据屏幕的一半。你可以根据需要添加更多的视图控制器和相应的TabBar按钮。这个例子使用了约束来布局子视图控制器的视图。