Adding a CarPlay UI

I am working on my current iPhone audio app that will be supported in CarPlay. I already got Apple approval, got development permission, and watched the video "Enabling the CarPlay App" ( https://developer.apple.com/videos/play/wwdc2017/719/ ). There is a Swift code snippet in the video demonstrating how to add CarPlay UI:

func updateCarWindow()  
{  
    guard let screen = UIScreen.screens.first(where: 
    { $0.traitCollection.userInterfaceIdiom == .carPlay })  
    else  
    {  
        // CarPlay is not connected  
        self.carWindow = nil;  
        return  
    }  

    // CarPlay is connected  
    let carWindow = UIWindow(frame: screen.bounds)  
    carWindow.screen = screen  
    carWindow.makeKeyAndVisible()  
    carWindow.rootViewController = CarViewController(nibName: nil, bundle: nil)  
    self.carWindow = carWindow
}

      

        
        
        
      

    

I rewrote it to the Objective-C version as shown below:

- (void) updateCarWindow  
{  
    NSArray *screenArray = [UIScreen screens];  

    for (UIScreen *screen in screenArray)  
    {        
        if (screen.traitCollection.userInterfaceIdiom == UIUserInterfaceIdiomCarPlay)  // CarPlay is connected.
        {  
            // Get the screen bounds so that you can create a window of the correct size.  
            CGRect screenBounds = screen.bounds;  

            UIWindow *tempCarWindow = [[UIWindow alloc] initWithFrame:screenBounds];  
            self.carWindow.screen = screen;  
            [self.carWindow makeKeyAndVisible];  

            // Set the initial UI for the window.  
            UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];  
            UIViewController *rootViewController = [storyboard instantiateViewControllerWithIdentifier:@"VC"];  

            self.carWindow.rootViewController = rootViewController;  
            self.carWindow = tempCarWindow;  

            // Show the window.  
            self.carWindow.hidden = NO; 

            return; 
        }  
    } 

    // CarPlay is not connected.
    self.carWindow = nil; 
}  

      

        
        
        
      

    

However, I found that the "screens" property of UIScreen always returns 1 item (main screen), regardless of whether it is tested on a real device or a simulator. So when my app is running on a simulator or real car with CarPlay, the app is just blank and says "Unable to connect to 'My app name'" (see image below). My ViewController has a simple UILabel though.

My question is, what should I do to get my app connected to CarPlay? That is, how do I get a screen that has the idiom UIUserInterfaceIdiomCarPlay and not just the main screen? Thanks a lot in advance.