iOS development study notes (OC language) - bottom tab bar

SceneDelegate.m

- (void)scene:(UIScene *)scene willConnectToSession:(UISceneSession *)session options:(UISceneConnectionOptions *)connectionOptions {
    // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
    // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
    // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
    
    UIWindowScene *windowScene = (UIWindowScene *)scene;
    self.window = [[UIWindow alloc] initWithWindowScene:windowScene];
    self.window.frame = windowScene.coordinateSpace.bounds;
    
    UITabBarController *tabBarController = [[UITabBarController alloc] init];
    
    UIViewController *controller1 = [[UIViewController alloc] init];
    controller1.view.backgroundColor = [UIColor redColor];
    controller1.tabBarItem.title = @"Tab1";
    controller1.tabBarItem.image = [UIImage imageNamed:@"icon.bundle/home"];
    controller1.tabBarItem.selectedImage = [UIImage imageNamed:@"icon.bundle/home_selected"];
    
    UIViewController *controller2 = [[UIViewController alloc] init];
    controller2.view.backgroundColor = [UIColor yellowColor];
    controller2.tabBarItem.title = @"Tab2";
    controller2.tabBarItem.image = [UIImage imageNamed:@"icon.bundle/video"];
    controller2.tabBarItem.selectedImage = [UIImage imageNamed:@"icon.bundle/video_selected"];
    
    UIViewController *controller3 = [[UIViewController alloc] init];
    controller3.view.backgroundColor = [UIColor blueColor];
    controller3.tabBarItem.title = @"Tab3";
    controller3.tabBarItem.image = [UIImage imageNamed:@"icon.bundle/like"];
    controller3.tabBarItem.selectedImage = [UIImage imageNamed:@"icon.bundle/like_selected"];
    
    UIViewController *controller4 = [[UIViewController alloc] init];
    controller4.view.backgroundColor = [UIColor greenColor];
    controller4.tabBarItem.title = @"Tab4";
    controller4.tabBarItem.image = [UIImage imageNamed:@"icon.bundle/page"];
    controller4.tabBarItem.selectedImage = [UIImage imageNamed:@"icon.bundle/page_selected"];
    
    [tabBarController setViewControllers: @[controller1, controller2, controller3, controller4]];
    
    tabBarController.tabBar.backgroundColor = [UIColor whiteColor];
        
    self.window.rootViewController = tabBarController;
    [self.window makeKeyAndVisible];
}