fix: deep and universal links

[thiagobrez]

Summary:

Fixes #138

Deep and Universal Links currently do not work on RN visionOS. Since iOS 13, if the project has opted into Scenes, lifecycle events are now controlled by SceneDelegate instead of AppDelegate.

After this PR is merged, we also need docs showing how to implement them, since the React Native docs only apply to non-Scene apps.

This PR is intended to be worked on. Currently, this solution works for Deep and Universal links when the app is already running or in background. When launching the app (previously killed) via Deep or Universal Links, Linking.getInitialUrl() will always return null, due to launchOptions being initialized as an empty object in RCTReactViewController.

The Apple Documentation indicates scene(_ :continue:) for handling Universal Links when app is already running, but that only applies to UIKit-based apps. For SwiftUI, the onOpenURL(_:perform:) view modifier must be used.

Final usage example for apps:

SceneDelegate.swift

class SceneDelegate: NSObject, UIWindowSceneDelegate {
  ...
  
  func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    // Other logic already present here
    ...
    
    // Deep Links and Universal Links - called when the app was previously NOT running
    RCTLinkingManager.scene(scene, willConnectTo: session, options: connectionOptions)
  }
  
  func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
      // Deep Links - called when the app was previously running or suspended
      RCTLinkingManager.scene(scene, openURLContexts: URLContexts)
  }
}

App.swift

struct visionaryApp: App {
  @UIApplicationDelegateAdaptor var delegate: AppDelegate
  
  var body: some Scene {
    WindowGroup {
      TabView {
        RCTRootViewRepresentable(moduleName: "myApp")
          .tabItem {
            Label("Home", systemImage: "house.fill")
          }
        RCTRootViewRepresentable(moduleName: "SettingsScreen")
          .tabItem {
            Label("Settings", systemImage: "gear")
          }
      }
      // Add the onOpenURL view modifier
      // Calling AppDelegate directly here but this should be improved to call SceneDelegate, probably
      .onOpenURL(perform: { (universalLink: URL) in
        delegate.onOpenURL(url: universalLink)
      })
    }

  }
}

AppDelegate.swift

class AppDelegate: RCTAppDelegate {
  ...
  
  // Universal Links - called when the app was previously running or suspended
  func onOpenURL(url: URL) {
    RCTLinkingManager.onOpen(url)
  }
}

Changelog:

[IOS] [ADDED] - Added equivalent scene method scene:willConnectTo:options: to handle Deep and Universal Links when app was previously NOT running
[IOS] [ADDED] - Added equivalent scene method scene:openURLContexts: to handle Deep Links when app was previously in background or suspended
[IOS] [ADDED] - Added equivalent scene method onOpenURL to handle Universal Links when app was previously in background or suspended

Test Plan:

• Deep Link (rntester://) with app previously killed, fetch initial URL via Linking.getInitialURL()
• Deep Link (rntester://) with app previously running or suspended, fetch incoming url via Linking.addEventListener('url', callback)
• Universal Link with app previously killed, fetch initial URL via Linking.getInitialURL()
• Universal Link with app previously running or suspended, fetch incoming url via Linking.addEventListener('url', callback)

[thiagobrez]

This should work, but the problem lies deeper because connectionOptions will come empty in the first place, due to the root View being started without launchOptions

[thiagobrez]

This is meant to capture the Universal Links coming from the SwiftUI onOpenURL view modifier

[okwasniewski]

I think we don't need to support both ways as the UIWindowSceneDelegate also handles universal links according to this page: https://developer.apple.com/documentation/xcode/supporting-universal-links-in-your-app

[okwasniewski]

So we should choose one or another

[okwasniewski]

Closed in favour of #140