Swift 5使用delegate方法触发popToViewController无响应问题咨询

数据老陈

2026-10-2

问题原因

你遇到的didLogout方法不执行的核心问题有3个：

弹出ViewController2时，没有给它的delegate属性赋值，导致delegate默认是nil，回调无法触发
ViewController1没有显式声明遵守LogoutDelegate协议
协议定义位置不合理，代理协议应该由触发回调的类（也就是ViewController2）持有，当前放在ViewController1中会导致ViewController2无法正常引用协议

修正方案（基于delegate实现）

1. 调整ViewController2（SettingsViewController）代码

将代理协议移到ViewController2中，同时用weak修饰delegate避免循环引用：

// 协议定义移到ViewController2内部
protocol LogoutDelegate: AnyObject {
    func didLogout()
}

class SettingsViewController: UIViewController {
    // 用weak修饰delegate，避免内存泄漏
    weak var delegate: LogoutDelegate?

    func logout() {
        print("Logout")
        self.delegate?.didLogout()
        dismiss(animated: true)
    }
}

2. 调整ViewController1代码

显式声明ViewController1遵守LogoutDelegate协议：

class ViewController1: UIViewController, LogoutDelegate {
    // 原有的didLogout实现保持不变
    func didLogout() {
        print("User Logged Out")
        self.navigationController?.popToRootViewController(animated: true)
    }
}

3. 修正弹出ViewController2的逻辑

创建ViewController2实例后，给它的delegate属性赋值为当前ViewController1实例：

let controller = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Test") as! SettingsViewController
// 新增这行，给delegate赋值
controller.delegate = self
let navigationController = UINavigationController(rootViewController: controller)
navigationController.modalPresentationStyle = .formSheet
self.present(navigationController, animated: true, completion: nil)