Creating a Tabbar

  

I haven’t seen many examples of creating a tabbar controller other than “theElements” example from Apple, which is pretty intense. So, what follows is a short snippet from a proof-of-concept application I was recently working on.
The basic idea is as follows: a UITabBarController contains an array of UIViewController objects, and these views are swapped when one of the tabbar buttons is clicked. You can see in the code below how I setup the view controllers that will be displayed for each tab, and add those controllers into the tabbar controller array.

The resulting tabbar looks as follows:

The interface file

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// // BirdBookAppDelegate.h   #import <UIKit/UIKit.h>   @interface BirdBookAppDelegate : NSObject <UIApplicationDelegate> { UINavigationController *navigationController; UIWindow *portraitWindow; UITabBarController *tabBarController; }   @property (nonatomic, retain) UINavigationController *navigationController; @property (nonatomic, retain) UITabBarController *tabBarController; @property (nonatomic, retain) UIWindow *portraitWindow;   @end

The implementation file

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// BirdBookAppDelegate.m   #import "BirdBookAppDelegate.h" #import "Bird.h" #import "AllBirds.h"   @implementation BirdBookAppDelegate   @synthesize navigationController; @synthesize tabBarController; @synthesize portraitWindow;   /*************************************************************************/ - (void) configureUI { // Create nav-controller for local use UINavigationController *localNavController;   // Create portrait window and content view (to hold other views) UIWindow *localPortraitWindow; localPortraitWindow = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; self.portraitWindow = localPortraitWindow; [localPortraitWindow release]; // Retained by delegate thru above setter   // Set background color [portraitWindow setBackgroundColor:[UIColor blackColor]];   // New tabbar controller and array to contain the view controllers // There are two (2) view controllers needed // One for "Identify Bird" and one for "Lookup Bird" tabBarController = [[UITabBarController alloc] init]; NSMutableArray *localViewControllersArray = [[NSMutableArray alloc] initWithCapacity:2];   /*-------------------------------------------------------------------- * Setup the 2 view controllers for the different data representations *-------------------------------------------------------------------*/   // Root view controller for "Identify Bird" IdentifyBirdRootViewController *vc; vc = [[IdentifyBirdRootViewController alloc] initWithStyle:UITableViewStylePlain]; localNavController = [[UINavigationController alloc] initWithRootViewController:vc]; localNavController.tabBarItem.image = [UIImage imageNamed:@"123.png"]; [vc release]; // This is now managed by the navigation controller   // Add navigation controller to the local vc array (1 of 2) [localViewControllersArray addObject:localNavController]; [localNavController release]; // Retained by above array   // Root view controller for "Lookup Bird" vc = [[LookupBirdRootViewController alloc] initWithStyle:UITableViewStyleGrouped]; localNavController = [[UINavigationController alloc] initWithRootViewController:vc]; localNavController.tabBarItem.image = [UIImage imageNamed:@"ABC.png"]; [vc release]; // This is now managed by the navigation controller   // Add navigation controller to the local vc array (2 of 2) [localViewControllersArray addObject:localNavController]; [localNavController release]; // Retained by above array   // Point the tab bar controllers view controller array to the array // of view controllers we just populated tabBarController.viewControllers = localViewControllersArray; [localViewControllersArray release]; // Retained thru above setter     // Add subview to portrait window to reference the tabbarcontroller [portraitWindow addSubview:tabBarController.view];   // Show it [portraitWindow makeKeyAndVisible]; }   /*************************************************************************/ - (void) applicationDidFinishLaunching:(UIApplication *)application { // Configure the user interface (tabbar, nav controllers, etc) [self configureUI]; }   /*************************************************************************/ - (void) dealloc { [tabBarController release]; [portraitWindow release]; [navigationController release]; [super dealloc]; }   @end