您可以使用Coordinator Pattern
例如,我有2个屏幕。第一个显示关于用户的信息,并从那里,他去屏幕选择他的城市。应该在第一个屏幕上显示有关已更改城市的信息。
final class CitiesViewController: UITableViewController {
// MARK: - Output -
var onCitySelected: ((City) -> Void)?
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
onCitySelected?(cities[indexPath.row])
}
...
}
UserEditViewController:
final class UserEditViewController: UIViewController, UpdateableWithUser {
// MARK: - Input -
var user: User? { didSet { updateView() } }
@IBOutlet private weak var userLabel: UILabel?
private func updateView() {
userLabel?.text = "User: \(user?.name ?? ""), \n"
+ "City: \(user?.city?.name ?? "")"
}
}
和协调者:
protocol UpdateableWithUser: class {
var user: User? { get set }
}
final class UserEditCoordinator {
// MARK: - Properties
private var user: User { didSet { updateInterfaces() } }
private weak var navigationController: UINavigationController?
// MARK: - Init
init(user: User, navigationController: UINavigationController) {
self.user = user
self.navigationController = navigationController
}
func start() {
showUserEditScreen()
}
// MARK: - Private implementation
private func showUserEditScreen() {
let controller = UIStoryboard.makeUserEditController()
controller.user = user
controller.onSelectCity = { [weak self] in
self?.showCitiesScreen()
}
navigationController?.pushViewController(controller, animated: false)
}
private func showCitiesScreen() {
let controller = UIStoryboard.makeCitiesController()
controller.onCitySelected = { [weak self] city in
self?.user.city = city
_ = self?.navigationController?.popViewController(animated: true)
}
navigationController?.pushViewController(controller, animated: true)
}
private func updateInterfaces() {
navigationController?.viewControllers.forEach {
($0 as? UpdateableWithUser)?.user = user
}
}
}
然后,我们只需要启动协调:
coordinator = UserEditCoordinator(user: user, navigationController: navigationController)
coordinator.start()
选中此https://stackoverflow.com/ a/45215000/7113238 – Lawliet
如果是你以前的VC,你可以使用上面的代码 –
你想发送数据回根视图控制器吗? – iDhaval