Firebaseプッシュ通知をObjective-Cで実装してみた ref: http://qiita.com/yonezawaizumi/items/fc9c37b08ad889304ff1

AppDelegate.m

@interface AppDelegate ()

// お知らせ表示用のナビゲーションコントローラー
@property(nonatomic, strong) UINavigationController *informationNavigationController;

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    // other initializing...

    // addTabViewControllerWithClassは別途実装
    self.informationNavigationController = [self addTabViewControllerWithClass:[InformationViewController class] viewControllers:viewControllers customizedViewControllers:customizableViewControllers];

    // other initializing...

    return YES;
}

- (void)changeTab {
    self.tabBarController.selectedViewController = self.informationNavigationController;
}