Swift:带有中心圆角按钮的自定义TabBar

import UIKit

class CustomTabBarController: UITabBarController, UITabBarControllerDelegate {

    let centerButton = UIButton(type: .custom)

    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置代理
        self.delegate = self
        
        // 设置tabBar的背景颜色和圆角
        tabBar.backgroundColor = .white
        tabBar.layer.cornerRadius = 25
        tabBar.clipsToBounds = true
        
        // 创建中心圆角按钮
        centerButton.setImage(UIImage(named: "plus"), for: .normal)
        centerButton.backgroundColor = .blue
        centerButton.layer.cornerRadius = 25
        centerButton.clipsToBounds = true
        centerButton.addTarget(self, action: #selector(centerButtonTapped), for: .touchUpInside)
        
        // 将中心按钮添加到tabBar上
        tabBar.addSubview(centerButton)
        tabBar.bringSubviewToFront(centerButton)
        
        // 设置中心按钮的frame
        centerButton.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            centerButton.centerXAnchor.constraint(equalTo: tabBar.centerXAnchor),
            centerButton.bottomAnchor.constraint(equalTo: tabBar.bottomAnchor, constant: -10),
            centerButton.widthAnchor.constraint(equalToConstant: 50),
            centerButton.heightAnchor.constraint(equalToConstant: 50)
        ])
    }
    
    @objc func centerButtonTapped() {
        // 在这里处理中心按钮的点击事件，例如切换到特定的视图控制器
        print("Center button tapped")
    }
    
    // 实现UITabBarControllerDelegate协议的方法
    func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
        // 在这里处理视图控制器的切换逻辑
        print("Selected view controller: \(viewController)")
    }
}