我想实现 TabBarController 并添加 Navigation Controller View 但徒劳无功

Question

我知道如何通过 Interface Builder 添加一个带有两个 TabBar 按钮的 TabBar。我将每个按钮链接到一个导航控制器。

现在我想学习如何以编程方式完成所有工作。现在我可以在模拟器中看到一个 TabBar，但上面没有按钮。有人可以帮我解决这个问题。谢谢！

这是 TabBarAppDelegate.h。

#import <UIKit/UIKit.h>
@interface TabBarAppDelegate : NSObject <UIApplicationDelegate> 
{
    UIWindow *window;
    UITabBarController *tabBarController;
    IBOutlet UINavigationController *navigationController1;
    IBOutlet UINavigationController *navigationController2;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) UITabBarController *tabBarController;
@property (nonatomic, retain) IBOutlet UINavigationController *navigationController1;
@property (nonatomic, retain) IBOutlet UINavigationController *navigationController2;
@end

这是 TabBarAppDelegate.m。

#import "TabBarAppDelegate.h"
#import "FirstViewController.h"
#import "SecondViewController.h"
@implementation TabBarAppDelegate
@synthesize window=window;
@synthesize tabBarController;
@synthesize navigationController1;
@synthesize navigationController2;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    tabBarController = [[UITabBarController alloc]init];   
    FirstViewController *firstViewController = [[FirstViewController alloc] initWithNibName:@"FirstViewController" bundle:nil];
    firstViewController.title = @"First";
    [self.navigationController1 pushViewController:firstViewController animated:NO];

    SecondViewController *secondViewController = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];
    secondViewController.title = @"NavCal";
    [self.navigationController2 pushViewController:secondViewController animated:NO];

    tabBarController.viewControllers = [NSArray arrayWithObjects:navigationController1, navigationController2, nil];

    [window addSubview:tabBarController.view];
    [self.window makeKeyAndVisible];
    [firstViewController release];
    [secondViewController release];
    return YES;
}

- (void)dealloc
{
    [tabBarController release];
    [window release];
    [super dealloc];
}

Answer 1

您似乎没有初始化导航视图控制器。看看这是否可行：

TabBarAppDelegate.h

• 移除属性 navigationController1 和 navigationController2

TabBarAppDelegate.m

• 替换

  [self.navigationController1 pushViewController:firstViewController animated:NO];
  

与

UINavigationController *navigationController1 = [[UINavigationController alloc] initWithRootViewController:firstViewController];

• 替换

  [self.navigationController2 pushViewController:secondViewController animated:NO];
  

与

UINavigationController *navigationController2 = [[UINavigationController alloc] initWithRootViewController:secondViewController];

• 将 navigationController1 和 navigationController2 添加到 tabBarController 后释放它们