UINavigationController doesn't work in a the m

问题:

I'm dealing with UINavigationControllers in my application, all handled by an UITabBarController. Everything works fine until my controllers fall into the automatically generated "More" tab.

I reproduced the problem in the simplistic example. Am I doing something wrong? I can't figure out.

Thanks for your help.

#import <UIKit/UIKit.h>

@interface testAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate>
{
    UIWindow *window;
    UITabBarController *tabBarController;
}
@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet UITabBarController *tabBarController;
@end

@implementation testAppDelegate
@synthesize window, tabBarController;

- (void)applicationDidFinishLaunching:(UIApplication *)application
{
    tabBarController = [[UITabBarController alloc] initWithNibName:nil bundle:nil];

    UINavigationController *ctrl1 = [[[UINavigationController alloc] initWithNibName:nil bundle: nil] autorelease];
    ctrl1.tabBarItem = [[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemFeatured tag:1] autorelease];

    UINavigationController *ctrl2 = [[[UINavigationController alloc] initWithNibName:nil bundle: nil] autorelease];
    ctrl2.tabBarItem = [[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemFavorites tag:2] autorelease];

    UINavigationController *ctrl3 = [[[UINavigationController alloc] initWithNibName:nil bundle: nil] autorelease];
    ctrl3.tabBarItem = [[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemBookmarks tag:3] autorelease];

    UINavigationController *ctrl4 = [[[UINavigationController alloc] initWithNibName:nil bundle: nil] autorelease];
    ctrl4.tabBarItem = [[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemContacts tag:4] autorelease];

    // This one won't work
    UINavigationController *ctrl5 = [[[UINavigationController alloc] initWithNibName:nil bundle: nil] autorelease];
    ctrl5.tabBarItem = [[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemMostRecent tag:5] autorelease];

    // This one will work
    UIViewController *ctrl6 = [[[UIViewController alloc] initWithNibName:nil bundle: nil] autorelease];
    ctrl6.tabBarItem = [[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemDownloads tag:6] autorelease];

    tabBarController.viewControllers = [NSArray arrayWithObjects:ctrl1, ctrl2, ctrl3, ctrl4, ctrl5, ctrl6, nil];

    [window addSubview:tabBarController.view];
    [window makeKeyAndVisible];
}

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

@end

回答1:

Short answer: you cannot nest navigation controllers

Longer answer: you are doing it wrong. A better way to create what you want goes like this:

NSMutableArray *viewControllers = [NSMutableArray array];

[viewControllers addObject:[[[ConverterViewController alloc] init] autorelease]];
[viewControllers addObject:[[[UINavigationController alloc]
                             initWithRootViewController:[[[CurrencyViewController alloc] init] autorelease]] autorelease]];
[viewControllers addObject:[[[UINavigationController alloc]
                             initWithRootViewController:[[[HistoryViewController alloc] init] autorelease]] autorelease]];
[viewControllers addObject:[[[UINavigationController alloc]
                             initWithRootViewController:[[[SetupViewController alloc] init] autorelease]] autorelease]];
[viewControllers addObject:[[[UINavigationController alloc]
                             initWithRootViewController:[[[HelpViewController alloc] init] autorelease]] autorelease]];
[viewControllers addObject:[[[LinksViewController alloc] init] autorelease]];

self.viewControllers = viewControllers;
self.customizableViewControllers = [viewControllers arrayByRemovingFirstObject];


@implementation HelpViewController

#pragma mark -
#pragma mark Initialization

- (id)init
{
    if ((self = [super initWithNibName:@"HelpView" bundle:nil]) != nil) {
        self.title = NSLocalizedString(@"Help", @"Help"); 
        self.tabBarItem.image = [UIImage imageNamed:@"question.png"];
    }

    return self;
}

回答2:

I think the problem might be that you are using the navigation controllers directly to push new views. Like this:

[ctrl4 pushViewController:next animated:true];

But if you are in the more tab another navigation controller is active. You must always get the current navigation controller using the navigationController property of the currently showing view controller.

By doing it this way, navigation controllers works just fine inside a tab bar controller.

回答3:

When you set the viewControllers property on the UITabBarController it will automatically replace the navigation controllers on the view controllers 5 onward with the moreNavigationController.

I dealt with a similar issue on my custom tab bar. This solution should help you:

Suppress moreNavigationController in custom UITabBarController