从TabBarController>NavigationController>ViewController > ViewController传递数据

class SecondViewController: UIViewController {
    var receivedData: String?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        if let data = receivedData {
            print("Received data: \(data)")
        }
    }
}

class FirstViewController: UIViewController {
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let destination = segue.destination as? SecondViewController {
            destination.receivedData = "Hello from FirstViewController"
        }
    }
}

protocol DataPassingDelegate: AnyObject {
    func passData(data: String)
}

class SecondViewController: UIViewController {
    weak var delegate: DataPassingDelegate?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // 假设在某个时刻调用代理方法传递数据
        delegate?.passData(data: "Data from SecondViewController")
    }
}

class FirstViewController: UIViewController, DataPassingDelegate {
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let destination = segue.destination as? SecondViewController {
            destination.delegate = self
        }
    }
    
    func passData(data: String) {
        print("Received data: \(data)")
    }
}

NotificationCenter.default.post(name: NSNotification.Name("DataPassed"), object: nil, userInfo: ["data": "Hello from FirstViewController"])

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(receiveData(_:)), name: NSNotification.Name("DataPassed"), object: nil)
}

@objc func receiveData(_ notification: Notification) {
    if let data = notification.userInfo?["data"] as? String {
        print("Received data: \(data)")
    }
}