如何使用单例方法推送视图控制器

Question

当我按下公共自定义视图中的按钮时，我想推送视图控制器，该按钮作为mainviewcontoller中的子视图添加。该方法应该在单例类中，以便在所有类中都有这个方法，如何做到这一点请建议我？

是否可以在singleton类中使用该方法？

 CreateContactViewController *contactList = [self.storyboard     instantiateViewControllerWithIdentifier:@"createContact"];
    [self.navigationController pushViewController:contactList animated:YES];

Answer 1

您应该获得可见视图控制器的UINavigationController实例并在其上推送视图控制器。

- (void)foo
{
     UIViewController *rootVC = [[UIApplication sharedApplication].keyWindow.rootViewController;
     UINavigationController *nc = [self topViewControllerWithRootViewController:rootVC].navigationController;
     if (nc) {
         CreateContactViewController *contactList = [nc.storyboard instantiateViewControllerWithIdentifier:@"createContact"];
         [nc pushViewController:contactList animated:YES];
     } else {
         // Here is the case when the visible view controller is presented modally and not embedded in UINavigationController. 
         // So here you can ONLY present your new view controller modally.
         // Or dismiss the modally presented one and then push your new view controller
     }
}

- (UIViewController*)topViewControllerWithRootViewController: (UIViewController*)rootViewController
{
    if ([rootViewController isKindOfClass:[UITabBarController class]]) {
        UITabBarController* tabBarController = (UITabBarController*)rootViewController;
        return [self topViewControllerWithRootViewController:tabBarController.selectedViewController];
    } else if ([rootViewController isKindOfClass:[UINavigationController class]]) {
        UINavigationController* navigationController = (UINavigationController*)rootViewController;
        return [self topViewControllerWithRootViewController:navigationController.visibleViewController];
    } else if (rootViewController.presentedViewController) {
        UIViewController* presentedViewController = rootViewController.presentedViewController;
        return [self topViewControllerWithRootViewController:presentedViewController];
    } else {
        return rootViewController;
    }
}