UIViewController的navigationController是零

Question

我试图访问navigationController距离UIViewController,由于某种原因,它等于nil

AppDelegate中:

self.mainViewController = [[MainViewController alloc] init];
self.navigationController = [[UINavigationController alloc] initWithRootViewController:self.mainViewController];
self.window.rootViewController = self.navigationController;

MainViewController:

 MyViewController *myViewController = [[MyViewController alloc] init];
[self.navigationController presentModalViewController:myViewController animated:YES];

有人遇到过这个问题吗？

谢谢!

Answer 1

UIViewController 可能没有 UINavigationController。
仅当您显式设置时，导航控制器才拥有某个控制器：

[yourNavController setViewControllers: @[ yourViewController1, ... , yourViewControllerN] ];