Support deeplinking using universal links

Summary:
## See the following [Proposal](https://fburl.com/gdoc/z90ch5in)

## Problem

We want to add support for universal links.
In order to do that, developers who have app events integration (AEM) will be required to add a call to the `openURL:` on the SDK delegate class from `application(_:continue:restorationHandler:)` in the short term.

We would like to simplify things for app developers since extracting the webpage URL from NSUserActivity may cause confusion and errors for deep linking.

## Solution

The better way is to just introduce a method with a similar signature to `application(_:continue:restorationHandler:)` in the SDK delegate.
Developers could simply invoke that method in order to have the universal link processed.

By doing that, we will to make FB SDK more accessible to developers.

## Testing

See the test plan section

Reviewed By: samodom

Differential Revision: D34786435

fbshipit-source-id: 289fea5ecc9e106fe0c9fcc94bf2a65b0c07c0ab

CHANGELOG.md

@@ -12,6 +12,27 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 [Full Changelog](https://github.com/facebook/facebook-ios-sdk/compare/v13.0.0...HEAD)
 
+### Notable Changes
+
+#### Added an API to support deep linking using Universal Links
+
+In order to ensure that your app properly supports [deep linking from app ads](https://developers.facebook.com/docs/app-ads/deep-linking) with Universal Links, you will need to implement `application(_:continue:restorationHandler:)` in your App Delegate, and call `ApplicationDelegate.shared.application(_:continue:)` from your implementation.
+Your change might look like the following snippet:
+
+```swift
+func application(
+  _ application: UIApplication,
+  continue userActivity: NSUserActivity,
+  restorationHandler: @escaping ([UIUserActivityRestoring]?) -> Void
+) -> Bool {
+  ApplicationDelegate.shared.application(application, continue: userActivity)
+
+  // Rest of implementation...
+
+  return true
+}
+```
+
 ## 13.0.0
 
 ### Notable Changes

FBSDKCoreKit/FBSDKCoreKit/FBSDKApplicationDelegate.m

@@ -189,6 +189,14 @@ static UIApplicationState _applicationState;
 
 #pragma mark - UIApplicationDelegate
 
+- (BOOL)application:(UIApplication *)application continueUserActivity:(NSUserActivity *)userActivity
+{
+  if (userActivity.activityType != NSUserActivityTypeBrowsingWeb) {
+    return NO;
+  }
+  return [self application:application openURL:userActivity.webpageURL options:@{}];
+}
+
 - (BOOL)application:(UIApplication *)application
             openURL:(NSURL *)url
             options:(NSDictionary<UIApplicationOpenURLOptionsKey, id> *)options

FBSDKCoreKit/FBSDKCoreKit/include/FBSDKApplicationDelegate.h

@@ -36,6 +36,18 @@ NS_SWIFT_NAME(ApplicationDelegate)
 @property (class, nonatomic, readonly, strong) FBSDKApplicationDelegate *sharedInstance
 NS_SWIFT_NAME(shared);
 
+/**
+ Call this method from the [UIApplicationDelegate application:continue:restorationHandler:] method
+ of the AppDelegate for your app. It should be invoked in order to properly process the web URL (universal link)
+ once the end user is redirected to your app.
+
+ @param application The application as passed to [UIApplicationDelegate application:continue:restorationHandler:].
+ @param userActivity The user activity as passed to [UIApplicationDelegate application:continue:restorationHandler:].
+
+ @return YES if the URL was intended for the Facebook SDK, NO if not.
+*/
+- (BOOL)application:(UIApplication *)application continueUserActivity:(NSUserActivity *)userActivity;
+
 /**
  Call this method from the [UIApplicationDelegate application:openURL:sourceApplication:annotation:] method
  of the AppDelegate for your app. It should be invoked for the proper processing of responses during interaction
@@ -49,7 +61,7 @@ NS_SWIFT_NAME(shared);
 
  @param annotation The annotation as passed to [UIApplicationDelegate application:openURL:sourceApplication:annotation:].
 
- @return YES if the url was intended for the Facebook SDK, NO if not.
+ @return YES if the URL was intended for the Facebook SDK, NO if not.
  */
 - (BOOL)application:(UIApplication *)application
             openURL:(NSURL *)url
@@ -67,7 +79,7 @@ NS_SWIFT_NAME(shared);
 
  @param options The options dictionary as passed to [UIApplicationDelegate application:openURL:options:].
 
- @return YES if the url was intended for the Facebook SDK, NO if not.
+ @return YES if the URL was intended for the Facebook SDK, NO if not.
  */
 - (BOOL)application:(UIApplication *)application
             openURL:(NSURL *)url

FBSDKCoreKit/FBSDKCoreKitTests/ApplicationDelegateTests.swift

@@ -528,6 +528,33 @@ final class ApplicationDelegateTests: XCTestCase {
     )
   }
 
+  func testOpeningUniversalLinkChecksAEMFeatureAvailability() {
+    // See https://developer.apple.com/documentation/xcode/supporting-universal-links-in-your-app
+    let userActivity = NSUserActivity(activityType: NSUserActivityTypeBrowsingWeb)
+    userActivity.webpageURL = SampleURLs.validUniversalLink
+    delegate.application(
+      UIApplication.shared,
+      continue: userActivity
+    )
+    XCTAssertTrue(
+      featureChecker.capturedFeaturesContains(.AEM),
+      "Opening a deep link should check if the AEM feature is enabled"
+    )
+  }
+
+  func testOpeningUniversalLinkNonBrowsingWebDoesNotCheckAEMAvailability() {
+    let userActivity = NSUserActivity(activityType: "Example")
+    userActivity.webpageURL = SampleURLs.validUniversalLink
+    delegate.application(
+      UIApplication.shared,
+      continue: userActivity
+    )
+    XCTAssertFalse(
+      featureChecker.capturedFeaturesContains(.AEM),
+      "Opening a deep link should check if the AEM feature is enabled"
+    )
+  }
+
   // MARK: - Application Observers
 
   func testDefaultsObservers() {

TestTools/TestTools/SampleURLs.swift

@@ -12,6 +12,7 @@ public enum SampleURLs {
   // swiftlint:disable force_unwrapping
   public static let valid = URL(string: "https://www.example.com")!
   public static let validApp = URL(string: "fb://test.com")!
+  public static let validUniversalLink = URL(string: "https://www.test.com")!
   public static let validPNG = URL(string: "https://www.example.com/babyamnimal.png")!
   // swiftlint:enable force_unwrapping