implement Facebook authentication demo

Author: yramanchuk

samples/objc/FirebaseUIChat/Info.plist

@@ -23,14 +23,33 @@
 		<dict>
 			<key>CFBundleTypeRole</key>
 			<string>Editor</string>
+			<key>CFBundleURLName</key>
+			<string>REVERSED_CLIENT_ID</string>
 			<key>CFBundleURLSchemes</key>
 			<array>
-				<string>REVERSED_CLIENT_ID</string>
+				<string>REPLACE_ME__WITH_REVERSED_CLIENT_ID</string>
+			</array>
+		</dict>
+		<dict>
+			<key>CFBundleTypeRole</key>
+			<string>Editor</string>
+			<key>CFBundleURLName</key>
+			<string>FACEBOOK_APP_ID</string>
+			<key>CFBundleURLSchemes</key>
+			<array>
+				<string>REPLACE_ME_WITH_FACEBOOK_APP_ID</string>
 			</array>
 		</dict>
 	</array>
 	<key>CFBundleVersion</key>
 	<string>1</string>
+	<key>LSApplicationQueriesSchemes</key>
+	<array>
+		<string>fbapi</string>
+		<string>fb-messenger-api</string>
+		<string>fbauth2</string>
+		<string>fbshareextension</string>
+	</array>
 	<key>LSRequiresIPhoneOS</key>
 	<true/>
 	<key>UILaunchStoryboardName</key>

samples/objc/FirebaseUIChat/Samples/Auth/FIRAuthViewController.m

@@ -25,6 +25,9 @@
 // Uncomment when using frawemorks
 //@import FirebaseGoogleAuthUI;
 #import <FIRGoogleAuthUI.h>
+// Uncomment when using frawemorks
+//@import FirebaseFacebookAuthUI;
+#import <FIRFacebookAuthUI.h>
 
 @interface FIRAuthViewController ()
 @property (weak, nonatomic) IBOutlet UITableViewCell *cellSignIn;
@@ -54,16 +57,27 @@ - (void)viewWillAppear:(BOOL)animated {
   [super viewWillAppear:animated];
 
   NSString *googleId = [[FIRApp defaultApp] options].clientID;
-  NSArray<id<FIRAuthProviderUI>> *providers = [NSArray arrayWithObjects:[[FIRGoogleAuthUI alloc] initWithClientID:googleId] , nil];
+  NSString *facebookAppId = [self readFacebookAppId];
+
+  NSArray<id<FIRAuthProviderUI>> *providers = [NSArray arrayWithObjects:
+                                               [[FIRGoogleAuthUI alloc] initWithClientID:googleId],
+                                               [[FIRFacebookAuthUI alloc] initWithAppID:facebookAppId],
+                                               nil];
   _authUI.providers = providers;
 
+  __weak FIRAuthViewController *weakSelf = self;
   self.authStateDidChangeHandle = [self.auth addAuthStateDidChangeListener:^(FIRAuth * _Nonnull auth, FIRUser * _Nullable user) {
-    [self updateUI:auth withUser:user];
+    [weakSelf updateUI:auth withUser:user];
   }];
 
 
 }
 
+-(void)viewDidDisappear:(BOOL)animated {
+  [super viewDidDisappear:animated];
+  [self.auth removeAuthStateDidChangeListener:self.authStateDidChangeHandle];
+}
+
 - (void)updateUI:(FIRAuth * _Nonnull) auth withUser:(FIRUser * _Nullable) user {
   self.authUser = user;
   if (user) {
@@ -97,5 +111,27 @@ - (IBAction)onAuthorization:(id)sender {
   }
 }
 
+#pragma mark - Helper Methods
+
+// Helper method to retrieve FB app ID from info.plist
+- (NSString *)readFacebookAppId {
+  NSString *facebookAppId = nil;
+  NSArray *urlTypes = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleURLTypes"];
+  for (NSDictionary *type in urlTypes) {
+    if ([(NSString *)type[@"CFBundleURLName"] isEqualToString:@"FACEBOOK_APP_ID"]) {
+      NSArray *urlSchemes = type[@"CFBundleURLSchemes"];
+      if (urlSchemes.count == 1) {
+        facebookAppId = urlSchemes.firstObject;
+        if (facebookAppId.length > 2) {
+          facebookAppId = [facebookAppId substringFromIndex:2];
+        }
+      }
+      break;
+    }
+  }
+
+  return facebookAppId;
+}
+
 
 @end