Handling Multiple Displays

When enClose detects an external display at runtime, the SceneDelegate automatically configures a new window using an instance of ExternalDisplayViewController. This controller initializes a full-screen web view, sized to match the external display's dimensions, and loads display.html from the www directory.

At the same time, the global boolean variable __EXTERNAL_DISPLAY__ is set to true.

Communicating with External Display

The native code can execute JavaScript on both the main and external displays using the evaluateJavascript method in the MainViewController class. The target argument for this function can be set to .main or .external, specifying where the JavaScript should be executed.

However, direct communication between the main and external web views is not possible. To bridge this gap, native code must act as an intermediary. We can implement a native method to execute JavaScript on the external display and invoke that method from the main web view:

// Function to execute javascript on external display
@objc func performJSOnExternalDisplay(_ params: [String: String]) {
    if let js = params["js"] {
        evaluateJavascript(javaScript: js, target: .external)
    }
}

From the main web view, we can call this native method using the following JavaScript:

// If external display is connected, we call the native method
if (typeof __EXTERNAL_DISPLAY__ != 'undefined' && __EXTERNAL_DISPLAY__ == true) {
    enClose({
        nativeCall: 'performJSOnExternalDisplay',
        data: {
            js: `
                console.log('Hello from main web view.');
                // JavaScript to be executed on the external display
                // ...
            `
        }
    });
}

Disabling the External Display

If you want to disable external display support and revert to iOS’s default behavior, you need to update Info.plist and SceneDelegate.swift.

Updating Info.plist

1. Open Info.plist in Xcode.
2. Locate the Application Scene Manifest key.
3. Under Scene Configuration, delete External Display Session Role Non-Interactive.

Updating SceneDelegate.swift

Modify the scene function as follows:

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    guard let windowScene = (scene as? UIWindowScene) else { return }

    // Set up the main view
    let mainViewController = MainViewController()
    let mainWindow = UIWindow(windowScene: windowScene)
    mainWindow.rootViewController = mainViewController
    self.window = mainWindow
    mainWindow.makeKeyAndVisible()
}

With these changes, your app will no longer load an external display. If mirrored on an Apple TV or an HDMI-connected display, only the main screen will be duplicated.