iPhone通过程序初始化选项卡栏控制器视图

我想通过编程来初始化我的标签栏控制器,但是我得到的代码只是一个空白屏幕。我试着模仿 TheElements sample app 一行行一行的东西看起来是可以比较的,但很明显有些问题。有什么建议吗?

谢谢。。。

M.

#import <UIKit/UIKit.h>

int main(int argc, char *argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    int retVal = UIApplicationMain(argc, argv, nil, @"DubbleWrapAppDelegate");
    [pool release];
    return retVal;
}

在dubblewrapappdelegate.h中:

@interface DubbleWrapAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate> {
    UIWindow *window;
    UITabBarController *tabBarController;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet UITabBarController *tabBarController;

@end

在dubblewrapappdelegate.m中:

@implementation DubbleWrapAppDelegate

@synthesize window;
@synthesize tabBarController;


- init {
    if (self = [super init]){
        // initialize to nil
        window = nil;
        tabBarController = nil;
    }
    return self;
}

- (void)applicationDidFinishLaunching:(UIApplication *)application {

    SafeTableViewController *vc1 = [[SafeTableViewController alloc] initWithStyle:UITableViewStylePlain];
    [vc1 setSafeItems:[SafeItem knownSafeItems]]; // Set the list of known SafeItems:
    UINavigationController *nc1;
    nc1 = [[UINavigationController alloc] initWithRootViewController:vc1];
    [vc1 release];


    BoxXRayTableViewController *vc2 = [[BoxXRayTableViewController alloc] initWithStyle:UITableViewStylePlain];
    UINavigationController *nc2;
    nc2 = [[UINavigationController alloc] initWithRootViewController:vc2];
    [vc2 release];

    AboutLibertyViewController *vc3 = [[AboutLibertyViewController alloc] init];
    UINavigationController *nc3;
    nc3 = [[UINavigationController alloc] initWithRootViewController:vc3];
    [vc3 release];

    NSArray* controllers = [NSArray arrayWithObjects:nc1, nc2, nc3, nil];

    tabBarController = [[UITabBarController alloc] init];
    tabBarController.viewControllers = controllers;
    [controllers release];

    // Add the tab bar controller's current view as a subview of the window
    window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    [window setBackgroundColor:[UIColor redColor]];
    [window addSubview:tabBarController.view];
    [window makeKeyAndVisible];

    [nc1 release];
    [nc2 release];
    [nc3 release];
}

设置plist时,没有引用NIB文件。