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Question

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我有AppDeligate文件：

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.

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

    self.recentView = [[RecentView alloc] initWithNibName:@"RecentView" bundle:nil];
    self.groupsView = [[GroupView alloc] initWithNibName:@"GroupView" bundle:nil];
    self.peopleView = [[PeopleView alloc] initWithNibName:@"PeopleView" bundle:nil];
    self.settingsView = [[SettingsView alloc] initWithNibName:@"SettingsView" bundle:nil];

    NavigationController *navController1 = [[NavigationController alloc] initWithRootViewController:self.recentView ];
    NavigationController *navController3 = [[NavigationController alloc] initWithRootViewController:self.groupsView];
    NavigationController *navController4 = [[NavigationController alloc] initWithRootViewController:self.peopleView];
    NavigationController *navController5 = [[NavigationController alloc] initWithRootViewController:self.settingsView];

       self.tabBarController = [[UITabBarController alloc] init];
    self.tabBarController.viewControllers = @[navController1, navController3, navController4, navController5];
    self.tabBarController.tabBar.translucent = NO;
    //self.tabBarController.selectedIndex = DEFAULT_TAB;

    self.window.rootViewController = self.tabBarController;
    [self.window makeKeyAndVisible];
    //---------------------------------------------------------------------------------------------------------------------------------------------
    [self.recentView view];
    [self.groupsView view];
    [self.peopleView view];
    [self.settingsView view];

    return YES;
}

在我的一个视图控制器中，我有：

@implementation GroupView
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self)
    {
        [self.tabBarItem setImage:[UIImage imageNamed:@"groupimage"]];
        self.tabBarItem.title = @"Groups";
    }

    return self;
}
- (void)viewDidLoad {
    [super viewDidLoad];
    self.title = @"Groups";


    // Uncomment the following line to preserve selection between presentations.
    // self.clearsSelectionOnViewWillAppear = NO;

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;

    //self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(actionNew)];
}

我使用Xcode 7.2，目标设置为iOS 9。