ios - UINavigationController 子类未在预期时调用 willShowViewController

Question

我使用 ECSlidingViewController 实现了一个带有样式菜单中幻灯片的应用程序

目前我有以下设置: ECSlidingViewController 的初始 View Controller 子类。这处理顶 View Controller (屏幕上显示的主视图)和左下 Controller (即菜单)的推送。

菜单是 TableView Controller 的子类，当单击一行时，新的顶 View Controller 将被插入堆栈。

根据previous question我使用一个导航 Controller (子类)，它包含一个 Root View Controller 。每次选择一行时，导航 Controller 的新实例都会加载不同的 View Controller ，旧的已释放。例如:

// Check if the settings view is currently displayed if it is just reset the top view else load it to the topviewcontroller.
                UINavigationController *navController = (UINavigationController *)self.slidingViewController.topViewController;
                UIViewController *VC = navController.topViewController;
                if ([VC isKindOfClass:[MESSettingsViewController class]]) {
                    [self.slidingViewController resetTopView];
                } else {
                    MESMainNavViewController *mainNavController = [[MESMainNavViewController alloc] initWithRootViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"SettingsVC"]];

                    __weak typeof(self) weakSelf = self;

                    [self.slidingViewController anchorTopViewOffScreenTo:ECRight animations:nil onComplete:^{
                        CGRect frame = self.slidingViewController.topViewController.view.frame;
                        self.slidingViewController.topViewController = mainNavController;
                        self.slidingViewController.topViewController.view.frame = frame;
                        [weakSelf.slidingViewController resetTopViewWithAnimations:nil onComplete:^{
                            [weakSelf updateCurrentCell];
                        }];
                    }];
                }

目前一切正常。我遇到的问题是登录顺序。如果用户注销，则会以模态方式推送不同的导航堆栈。用户成功登录后，就会发出通知。这是由初始 View Controller 接收的(从上面):

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didLoginUser) name:@"LoginCompleteNotification" object:nil];

然后，该方法将用户推送到相关子类导航 Controller 的新实例，并将主 Controller 作为根。

// If the view controller is not home send them to home
UINavigationController *navController = (UINavigationController *)self.topViewController;
UIViewController *VC = navController.topViewController;
if (![VC isKindOfClass:[MESHomeViewController class]]) {
    UIStoryboard *storyboard;

    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
        storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard_iPhone" bundle:nil];
    } else if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
        storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard_iPad" bundle:nil];
    }

    MESMainNavViewController *mainNavController = [[MESMainNavViewController alloc] initWithRootViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"HomeVC"]];

    self.topViewController = mainNavController;
    [self resetTopView];

}

问题似乎出在以下部分:

MESMainNavViewController *mainNavController = [[MESMainNavViewController alloc] initWithRootViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"HomeVC"]];

self.topViewController = mainNavController;

当创建导航 Controller 的这个新实例时，委托(delegate)方法 willShowViewController 似乎没有被调用？我不明白为什么，当通过菜单 TableView 更改 Controller 时它会调用它，并且它使用相同的方法来创建，有什么想法吗？

Answer 1

苹果文档指出

The UINavigationControllerDelegate protocol defines methods a navigation controller delegate can implement to change the behavior when view controllers are pushed and popped from the stack of a navigation controller.

因此，我认为仅当您向导航堆栈推送或弹出 View Controller 时才会调用 willShowViewController 方法。