ios 如何以编程方式将 UINavigationController 添加到现有 UIViewController

How to add an UINavigationController to an existing UIViewController programmatically

提问by photosynthesis

I am newbie to iOS programming, and this problem may seem stupid to someone, I am sorry. I have a problem here is that I have an existing UIViewController (A), and another UIViewController (B), I want to add an UINavigationController to A such that when I press a button on A, I will be lead to B. I tried the following approach, but it does not solve the problem:

我是 iOS 编程的新手，这个问题对某些人来说可能很愚蠢，我很抱歉。我这里有一个问题是我有一个现有的 UIViewController (A) 和另一个 UIViewController (B)，我想向 A 添加一个 UINavigationController，这样当我按下 A 上的按钮时，我会被引导到 B。我试过了以下方法，但并不能解决问题：

in AppDelegate:

在 AppDelegate 中：

@synthesize navigationController;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.

    self.tabbarController = [[UITabBarController alloc] init];
    UIViewController *viewController_1 = [[WUSTLViewController_1 alloc] init];
    UIViewController *viewController_2 = [[WUSTLViewController_2 alloc] init];

    UIViewController *viewController_3 = [[WUSTLViewController_3 alloc] init];
    navigationController = [[UINavigationController alloc] initWithRootViewController: viewController_3];

    self.tabbarController.viewControllers = [NSArray arrayWithObjects:viewController_1, viewController_2, navigationController, nil];
    self.window.rootViewController = self.tabbarController;

    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}

In WUSTLViewController_3.h (A):

在 WUSTLViewController_3.h (A) 中：

#import <UIKit/UIKit.h>
#import "WUSTLViewController_4.h"

@interface WUSTLViewController_3 : UIViewController {
    WUSTLViewController_4 *viewController_4;
}

@property UINavigationController *navigationController;

@end

In WUSTLViewController_3.m (A):

在 WUSTLViewController_3.m (A) 中：

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    viewController_4 = [[WUSTLViewController_4 alloc] init];

    UIButton *myButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    myButton.frame = CGRectMake(80, 50, 150, 40);
    [myButton setTitle:@"Push" forState:UIControlStateNormal];
    [myButton addTarget:self action:@selector(pressButton:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:myButton];
}

- (IBAction)pressButton:(id)sender
{
    [self.navigationController pushViewController:viewController_4 animated:YES];
}

When I click the button, nothing happened.

当我点击按钮时，什么也没发生。

回答by Rob Jones

This is not how UINavigationControllerswork. You need to set A as the rootViewControllerof your UINavigationController. UINavigationController is a container for other view controllers.

这不是UINavigationControllers工作的方式。您需要将 A 设置为rootViewController您的UINavigationController. UINavigationController 是其他视图控制器的容器。

For example, in your AppDelegateyou might do something like this:

例如，在你的AppDelegate你可能会做这样的事情：

UIViewController *A = [[UIViewController alloc] init];    
UINavigationController *navVC = [[UINavigationController alloc] initWithRootViewController:A];
UIViewController *X = [[UIViewController alloc] init];
UIViewController *Y = [[UIViewController alloc] init];
UIViewController *Z = [[UIViewController alloc] init];
UITabBarController *tabVC = [[UITabBarController alloc] init];
tabVC.viewControllers = @[X, Y, Z, navVC];
self.window.rootViewController = tabVC;

And in A

而在 A

- (IBAction)pressButton:(id)sender
{
    [self.navigationController pushViewController:B animated:YES];
}

回答by Jeffery Thomas

The problem is A needs to be in a navigation controller before you can push B.

问题是 A 需要在导航控制器中才能推送 B。

If A is already in a navigation controller:

如果 A 已经在导航控制器中：

[A.navigationController pushViewController:B animated:YES];

If A is not in a navigation controller, then you need to think about how you want your app's views laid out.

如果 A 不在导航控制器中，那么您需要考虑如何布置应用程序的视图。

1. Put A in a navigation controller.
2. Present a navigation controller from A as a presented view controller.

1. 将 A 放入导航控制器中。
2. 将 A 中的导航控制器呈现为呈现的视图控制器。

If you go for option 1, then by the time A is loaded, it will already be in a navigation controller. You only need to push B.

如果您选择选项 1，那么在加载 A 时，它已经在导航控制器中。你只需要推B。

[A.navigationController pushViewController:B animated:YES];

If you go for option 2, then you need to present the navigation controller from A.

如果您选择选项 2，那么您需要展示 A 中的导航控制器。

UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:B];
[A presentViewController:navigationController animated:YES completion:NULL];

NOTE: This will create a new navigation stack with B as the root. You will need to have some way to dismiss the navigation controller, when you are done.

注意：这将创建一个以 B 为根的新导航堆栈。完成后，您需要有一些方法来关闭导航控制器。

[A dismissViewControllerAnimated:YES completion:NULL];

If you want to dismiss the navigation controller from within B, then you need to do the following.

如果要从 B 中关闭导航控制器，则需要执行以下操作。

[B.navigationController.presentingViewController dismissViewControllerAnimated:YES completion:NULL];

That is from B, get the navigation controller, and from the navigation controller, get the presenting view controller (which is A).

即从 B 获取导航控制器，从导航控制器获取呈现视图控制器（即 A）。