Firebase Options Documentation (#10510)

Author: paulb777

FirebaseCore/Sources/Public/FirebaseCore/FIROptions.h

@@ -31,7 +31,7 @@ NS_SWIFT_NAME(FirebaseOptions)
 + (nullable FIROptions *)defaultOptions NS_SWIFT_NAME(defaultOptions());
 
 /**
- * An iOS API key used for authenticating requests from your app, e.g.
+ * An API key used for authenticating requests from your Apple app, e.g.
  * The key must begin with "A" and contain exactly 39 alphanumeric characters, used to identify your
  * app to Google servers.
  */
@@ -44,19 +44,19 @@ NS_SWIFT_NAME(FirebaseOptions)
 @property(nonatomic, copy) NSString *bundleID;
 
 /**
- * The OAuth2 client ID for iOS application used to authenticate Google users, for example
+ * The OAuth2 client ID for Apple applications used to authenticate Google users, for example
  * @"12345.apps.googleusercontent.com", used for signing in with Google.
  */
 @property(nonatomic, copy, nullable) NSString *clientID;
 
 /**
- * The tracking ID for Google Analytics, e.g. @"UA-12345678-1", used to configure Google Analytics.
+ * Unused.
  */
 @property(nonatomic, copy, nullable) NSString *trackingID;
 
 /**
  * The Project Number from the Google Developer's console, for example @"012345678901", used to
- * configure Google Cloud Messaging.
+ * configure Firebase Cloud Messaging.
  */
 @property(nonatomic, copy) NSString *GCMSenderID NS_SWIFT_NAME(gcmSenderID);
 
@@ -66,8 +66,7 @@ NS_SWIFT_NAME(FirebaseOptions)
 @property(nonatomic, copy, nullable) NSString *projectID;
 
 /**
- * The Android client ID used in Google AppInvite when an iOS app has its Android version, for
- * example @"12345.apps.googleusercontent.com".
+ * Unused.
  */
 @property(nonatomic, copy, nullable) NSString *androidClientID;
 

docs/FirebaseOptionsPerProduct.md

@@ -0,0 +1,77 @@
+# Firebase Options Usage By Product
+
+Summarize which Firebase Options fields (and GoogleService-Info.plist attributes) are used by which Firebase products.
+
+|                       | An    | ApC   | ApD   | Aut   | Cor   | Crs   | DB    | DL    | Fst   | Fn    | IAM   | Ins   | Msg   | MLM   | Prf   | RC    | Str   |
+|   :---                | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: |
+| **apiKey**            |       |  ✅   |  ✅  |  ✅   |       |       |       |  ✅   |       |       |  ✅   |  ✅   |       |     |  ✅  |   ✅    |      |
+| **bundleID**          |       |       |       |       |   ✅  |       |       |       |       |       |       |       |       |       | ✅   |       |     |
+| **clientID**          |       |       |       |  ✅   |       |       |       |       |       |       |       |       |       |       |       |       |     |
+| **gcmSenderID**       |       |       |       |       |       |       |       |       |       |       |   ✅  |   ✅  |  ✅  |       |       |  ✅   |      |
+| **projectID**         |       |   ✅  |       |       |       |       |   ✅ |       |  ✅  |  ✅   |        |  ✅   |       |  ✅  |   ✅  |  ✅   |       |
+| **googleAppID**       |   ✅  |  ✅   |       |  ✅  |       |  ✅   |   ✅ |       |       |       |   ✅   |   ✅  | ✅   |       |  ✅   |   ✅ |   ✅ |
+| **databaseURL**       |       |       |       |       |       |       |   ✅  |       |       |       |       |       |       |       |       |       |       |
+| **deepLinkURLScheme** |       |       |       |       |       |       |       |    ✅ |       |       |       |       |       |       |       |       |       |
+| **storageBucket**     |       |       |       |       |       |       |       |       |       |       |       |       |       |       |       |       |   ✅   |
+
+
+## Rows (FirebaseOptions)
+See [FIROptions.m](https://github.com/firebase/firebase-ios-sdk/blob/master/FirebaseCore/Sources/FIROptions.m) to see how the variables map
+to GoogleService-Info.plist attributes.
+
+* *apiKey*: An API key used for authenticating requests from your Apple app
+* *bundleID*: The bundle ID for the application (Not used by the SDK)
+* *clientID*: The OAuth2 client ID for Apple applications used to authenticate Google users
+* *gcmSenderID*: The Project Number from the Google Developer's console used to configure Google Cloud Messaging
+* *projectID*: The Project ID from the Firebase console
+* *googleAppID*: The Google App ID that is used to uniquely identify an instance of an app
+* *databaseURL*: The realtime database root URL
+* *deepLinkURLScheme*: The URL scheme used to set up Durable Deep Link service
+* *storageBucket*: The Google Cloud Storage bucket name
+
+## Questions
+
+* *apiKey*, *projectID*, *gcmSenderID*, *projectID*, and *googleAppID* seem to have overlapping
+  functionality. Can they be consolidated?
+* *gcmSenderID* is the second subfield of *googleAppID*. Can it be eliminated?
+* *bundleID* seems to have three purposes: Performance SDK uses it. Messaging back end uses it. Core
+  will generate an error message if it doesn't match the actual bundleID. Anything else?
+* Why isn't *deepLinkURLScheme* set from the GoogleService-Info.plist field `REVERSED_CLIENT_ID` like
+  other Firebase Options? The client code is required to explicitly set it.
+* Is there a better way to manage the fields that are only used by one product? *clientID*, *databaseURL*,
+  *deepLinkURLScheme*, and *storageBucket*.
+
+## Unused FirebaseOptions
+Proposal: Deprecate these in the SDK and stop generating them for GoogleService-Info.plist.
+
+* *androidClientID*
+* *trackingID*
+
+## Unread GoogleService-Info.plist fields
+Proposal: Stop generating these for GoogleService-Info.plist.
+
+ * PLIST_VERSION
+ * IS_ADS_ENABLED
+ * IS_ANALYTICS_ENABLED
+ * IS_APPINVITE_ENABLED
+ * IS_GCM_ENABLED
+ * IS_SIGNIN_ENABLED
+
+## Columns (Firebase Products)
+* An - Analytics
+* ApC - App Check
+* ApD - App Distribution
+* Aut - Auth
+* Cor - Core
+* Crs - Crashlytics
+* DB - Real-time Database
+* DL - Dynamic Links
+* Fst - Firestore
+* Fn - Functions
+* IAM - In App Messaging
+* Ins - Installations
+* Msg - Messaging
+* MLM - MLModel Downloader
+* Prf - Performance
+* RC - Remote Config
+* Str - Storage