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Coordinator 模式

问题​

Coordinator 解决什么问题？如何实现？

答案​

问题背景​

ViewController 直接管理导航 → VC 之间强耦合、难以测试、难以复用。

// ❌ VC 耦合导航逻辑
class UserListVC: UIViewController {
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let detailVC = UserDetailVC(user: users[indexPath.row])
        navigationController?.pushViewController(detailVC, animated: true)
    }
}

Coordinator 实现​

protocol Coordinator: AnyObject {
    var childCoordinators: [Coordinator] { get set }
    var navigationController: UINavigationController { get set }
    func start()
}

class UserCoordinator: Coordinator {
    var childCoordinators: [Coordinator] = []
    var navigationController: UINavigationController

    init(nav: UINavigationController) {
        self.navigationController = nav
    }

    func start() {
        let vm = UserListViewModel()
        vm.onSelectUser = { [weak self] user in
            self?.showDetail(user: user)
        }
        let vc = UserListVC(viewModel: vm)
        navigationController.pushViewController(vc, animated: true)
    }

    private func showDetail(user: User) {
        let detailVC = UserDetailVC(user: user)
        navigationController.pushViewController(detailVC, animated: true)
    }
}

SwiftUI 中的简化方案​

SwiftUI 用 NavigationStack + 枚举路由替代传统 Coordinator：

enum Route: Hashable {
    case userDetail(User)
    case settings
}

struct AppCoordinatorView: View {
    @State private var path = NavigationPath()

    var body: some View {
        NavigationStack(path: $path) {
            UserListView(path: $path)
                .navigationDestination(for: Route.self) { route in
                    switch route {
                    case .userDetail(let user):
                        UserDetailView(user: user)
                    case .settings:
                        SettingsView()
                    }
                }
        }
    }
}

常见面试问题​

Q1: Coordinator 和 Router 的区别？​

答案：Router 只负责"跳到哪"（URL → VC 映射），Coordinator 更重，负责整个导航流程的协调（创建 VC、传参、管理子 Coordinator）。

相关链接​