add Universal Links support to Linking.getInitialURL(). Fixes #6099

Summary:Currently, Linking.getInitialURL() only supports custom URL scheme and not Universal Links. This PR fixes that. see #6099
Closes #6147

Differential Revision: D2976902

Pulled By: javache

fb-gh-sync-id: 750fe4a7c251ba57433c3a24866a4a510f125069
shipit-source-id: 750fe4a7c251ba57433c3a24866a4a510f125069

Libraries/LinkingIOS/RCTLinkingManager.m

@@ -33,7 +33,18 @@ - (void)setBridge:(RCTBridge *)bridge
 
 - (NSDictionary<NSString *, id> *)constantsToExport
 {
-  NSURL *initialURL = _bridge.launchOptions[UIApplicationLaunchOptionsURLKey];
+  NSURL *initialURL;
+
+  if (_bridge.launchOptions[UIApplicationLaunchOptionsURLKey]) {
+    initialURL = _bridge.launchOptions[UIApplicationLaunchOptionsURLKey];
+  } else if (_bridge.launchOptions[UIApplicationLaunchOptionsUserActivityDictionaryKey]) {
+    NSDictionary *userActivityDictionary = _bridge.launchOptions[UIApplicationLaunchOptionsUserActivityDictionaryKey];
+
+    if ([userActivityDictionary[UIApplicationLaunchOptionsUserActivityTypeKey] isEqual:NSUserActivityTypeBrowsingWeb]) {
+      initialURL = ((NSUserActivity *)userActivityDictionary[@"UIApplicationLaunchOptionsUserActivityKey"]).webpageURL;
+    }
+  }
+
   return @{@"initialURL": RCTNullIfNil(initialURL.absoluteString)};
 }