[英]UIBarButtonItem will not show when I segue programmatically
我正在构建一个应用程序,我在其中以编程方式从 ViewControllerA 转场,因为它是一个菜单项列表,每个菜单项都指向不同的 VC,因此我没有多个转场,而是在代码中实例化视图控制器。 我的问题是,即使我的故事板上有一个 Bar 按钮项目,它也不会显示在应用程序中。
视图控制器 A 菜单模型代码:
class PlayerMenu: Hashable {
let title: String
let numberOfItems: String
let menuItemViewController: UIViewController.Type?
init(title: String, numberOfItems: String, viewController: UIViewController.Type? = nil) {
self.title = title
self.numberOfItems = numberOfItems
self.menuItemViewController = viewController
}
func hash(into hasher: inout Hasher) {
hasher.combine(identifier)
}
static func == (lhs: PlayerMenu, rhs: PlayerMenu) -> Bool {
return lhs.identifier == rhs.identifier
}
private let identifier = UUID()
}
视图控制器代码
private lazy var menuItems: [PlayerMenu] = {
return [
PlayerMenu(title: "Status", numberOfItems: "Available.", viewController: nil),
PlayerMenu(title: "Pertinent Medical History", numberOfItems: "", viewController: nil),
PlayerMenu(title: "Injury / Illness", numberOfItems: "There are no injuries.", viewController: nil),
PlayerMenu(title: "Allergy", numberOfItems: "There are no allergies.", viewController: AllergyTableViewController.self),
PlayerMenu(title: "Neurocognitive", numberOfItems: "Unavailable.", viewController: nil),
PlayerMenu(title: "Medication", numberOfItems: "There are no medications.", viewController: nil),
PlayerMenu(title: "Immunization", numberOfItems: "There are no immunizations", viewController: nil),
PlayerMenu(title: "Dictations", numberOfItems: "There are no dictations.", viewController: nil),
PlayerMenu(title: "Imaging", numberOfItems: "There is no imaging.", viewController: nil),
PlayerMenu(title: "Participation", numberOfItems: "Unavailable.", viewController: nil),
PlayerMenu(title: "Away Game Injury", numberOfItems: "Unavailable.", viewController: nil),
]
}()
ViewControllerA 转场
extension PlayerDashboardViewController: UITableViewDelegate {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
guard let menuItem = self.dataSource.itemIdentifier(for: indexPath) else { return }
if let viewController = menuItem.menuItemViewController {
let navController = UINavigationController(rootViewController: viewController.init())
present(navController, animated: true)
}
}
}
您没有看到您在故事板中设计的视图控制器的原因是因为调用viewController.init()
不会从故事板实例化您的视图控制器。 您需要致电:
UIStoryboard.instantiateViewController(withIdentifier:)
或者(仅适用于 iOS 13+):
UIStoryboard.instantiateViewController(identifier:creator:)
我建议不要在PlayerMenu
类中存储视图控制器类型,而是存储视图控制器的故事板标识符,如下所示:
class PlayerMenu: Hashable {
let title: String
let numberOfItems: String
let menuItemViewControllerStoryboardIdentifier: String?
init(title: String, numberOfItems: String, viewControllerStoryboardIdentifier: String? = nil) {
self.title = title
self.numberOfItems = numberOfItems
self.menuItemViewControllerStoryboardIdentifier = viewControllerStoryboardIdentifier
}
[...]
}
然后当你想实例化你的视图控制器时,获取对你的故事板的引用(如果它与当前视图控制器的故事板相同,那么你可以说self.storyboard
,否则直接使用UIStoryboard.init(name:bundle:)
创建故事板UIStoryboard.init(name:bundle:)
):
extension PlayerDashboardViewController: UITableViewDelegate {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
guard let menuItem = self.dataSource.itemIdentifier(for: indexPath),
let viewControllerStoryboardIdentifier = menuItem.menuItemViewControllerStoryboardIdentifier,
let viewController = self.storyboard?.instantiateViewController(withIdentifier: viewControllerStoryboardIdentifier) else {
return
}
let navController = UINavigationController(rootViewController: viewController)
present(navController, animated: true)
}
}
然后确保在你的故事板中给你的视图控制器标识符,并像这样创建你的PlayerMenu
项目:
PlayerMenu(title: "Allergy", numberOfItems: "There are no allergies.", viewControllerStoryboardIdentifier: "AllergyTableViewController (or whatever identifier you give this in your storyboard)")
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