Adding a TabBarController programmatically

问题:

I want to make a tab bar controller and navigation controller programmatically. My code works so far that it shows a tab bar at the bottom, but the OptionViewController doesn't say anything (no title) on the button of the second tab bar. The funny thing is, when i click the button without anything on it, the title appears (and so is his view), can someone explain to me what i am doing wrong? I tried to use the following code:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{    
    // Override point for customization after application launch.
    [self.window makeKeyAndVisible];

    NSMutableArray *tabItems = [[NSMutableArray alloc] initWithCapacity:2];

    DefaultViewController *dvc = [[DefaultViewController alloc] init];
    UINavigationController *dvc_nc = [[UINavigationController alloc] initWithRootViewController:dvc];
    [tabItems addObject:dvc_nc];
    [dvc release];
    [dvc_nc release];

    OptionsViewController *ovc = [[OptionsViewController alloc] initWithStyle:UITableViewStyleGrouped];
    UINavigationController *ovc_nc = [[UINavigationController alloc] initWithRootViewController:ovc];
    [tabItems addObject:ovc_nc];
    [ovc release];
    [ovc_nc release];

    UITabBarController *tbc = [[UITabBarController alloc] init];
    tbc.viewControllers = tabItems;
    self.tabController = tbc;
    [tabItems release];
    [tbc release];

    [self.window addSubview:self.tabController.view];

    return YES;
}

回答1:

You need to set the tabBarItem and title of the UINavigationController and not its root viewController.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{    
    // Override point for customization after application launch.
    [self.window makeKeyAndVisible];

    NSMutableArray *tabItems = [[NSMutableArray alloc] initWithCapacity:2];

    DefaultViewController *dvc = [[DefaultViewController alloc] init];
    UINavigationController *dvc_nc = [[UINavigationController alloc] initWithRootViewController:dvc];
    dvc_nc.tabBarItem.title = @"Default";
    dvc_nc.tabBarItem.image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"Default" ofType:@"png"]];
    [tabItems addObject:dvc_nc];
    [dvc release];
    [dvc_nc release];

    OptionsViewController *ovc = [[OptionsViewController alloc] initWithStyle:UITableViewStyleGrouped];
    UINavigationController *ovc_nc = [[UINavigationController alloc] initWithRootViewController:ovc];
    ovc_nc.tabBarItem.title = @"Option"
    ovc_nc.tabBarItem.image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"Optiomn" ofType:@"png"]];

    [tabItems addObject:ovc_nc];
    [ovc release];
    [ovc_nc release];

    UITabBarController *tbc = [[UITabBarController alloc] init];
    tbc.viewControllers = tabItems;
    self.tabController = tbc;
    [tabItems release];
    [tbc release];

    [self.window addSubview:self.tabController.view];

    return YES;
}

回答2:

I created the UITabbarController as rooview controller of the app with UINavigationController for UIViewController.

here one more example: I used xibs for View Controllers.

AppDelegate.m

I create a method name: setupAppHome

#pragma mark - SETUP HOME
-(void) setupAppHome{
    NSLog(@"set up the nano home");

    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    if (_chatViewController == nil) {
        _chatViewController = [[ChatViewController alloc] initWithNibName:@"ChatViewController" bundle:nil];
        chatNav = [[UINavigationController alloc] initWithRootViewController:_chatViewController];
        chatNav.tabBarItem.title=@"Chat";
        chatNav.tabBarItem.image=[UIImage imageNamed:@"chat_icon.png"];

    }
    if (_callController == nil) {
        _callController = [[CallViewController alloc] initWithNibName:@"CallViewController" bundle:nil];
        callNav = [[UINavigationController alloc] initWithRootViewController:_callController];
        callNav.tabBarItem.title=@"Call";
        callNav.tabBarItem.image=[UIImage imageNamed:@"call_icon.png"];

    }
    if (_contanctsController == nil) {
        _contanctsController = [[ContactsViewController alloc] initWithNibName:@"ContactsViewController" bundle:nil];
        conNav = [[UINavigationController alloc] initWithRootViewController:_contanctsController];
        conNav.tabBarItem.title=@"Contact";
        conNav.tabBarItem.image=[UIImage imageNamed:@"contact_icon.png"];

    }
    if (_settingController == nil) {
        _settingController = [[SettingViewController alloc] initWithNibName:@"SettingViewController" bundle:nil];
        settingNav = [[UINavigationController alloc] initWithRootViewController:_settingController];
        settingNav.tabBarItem.title=@"Setting";
        settingNav.tabBarItem.image=[UIImage imageNamed:@"setting_icon.png"];

    }

    self.tabController = [[UITabBarController alloc] init];

    NSMutableArray          *controllers = [[NSMutableArray alloc] initWithCapacity:4];
    [controllers addObject:chatNav];
    [controllers addObject:callNav];
    [controllers addObject:conNav];
    [controllers addObject:settingNav];


    self.tabController.viewControllers = controllers;//@[chatNav,callNav,conNav,settingNav];

    self.tabController.selectedIndex=0;



    [self.window setRootViewController:self.tabController];
    [self.window makeKeyAndVisible];


}

It is texted in Xcode 9 with iOS 11.

回答3:

If someone needs a SWIFT version. This worked for me. Thanks @rckoenes for the objC answer I used to translate this from.

    window?.makeKeyAndVisible()

    let dvc = HomeViewController()
    let dvc_nc = UINavigationController(rootViewController: dvc)
        dvc_nc.tabBarItem.title = "Home"
        dvc_nc.tabBarItem.image = UIImage(named: "HomeIcon")
    controllers.append(dvc_nc)

    let ovc = ProfileViewController()
    let ovc_nc = UINavigationController(rootViewController: ovc)
        ovc_nc.tabBarItem.title = "Profile"
        ovc_nc.tabBarItem.image = UIImage(named: "ProfileIcon")
    controllers.append(ovc_nc)

    let tbc = UITabBarController()
        tbc.viewControllers = controllers

    window?.rootViewController = tbc

    UINavigationBar.appearance().tintColor = UIColor(red: 0.05, green: 0.47, blue: 0.91, alpha: 1.0)
    UINavigationBar.appearance().barTintColor = UIColor(red: 0.05, green: 0.47, blue: 0.91, alpha: 1.0)
    UINavigationBar.appearance().titleTextAttributes = [NSForegroundColorAttributeName: UIColor.whiteColor()]
    UIApplication.sharedApplication().statusBarStyle = UIStatusBarStyle.LightContent