您可以将 Facebook 登录或 Facebook 受限登录机制集成到您的应用中，让您的用户可使用自己的 Facebook 帐号进行 Firebase 身份验证。
准备工作
使用 Swift Package Manager 安装和管理 Firebase 依赖项。
- 在 Xcode 中打开您的应用项目，依次转到 File > Add Packages。
- 出现提示时，添加 Firebase Apple 平台 SDK 代码库：
- 选择 Firebase Authentication 库。
- 完成之后，Xcode 将会自动开始在后台解析和下载您的依赖项。
https://github.com/firebase/firebase-ios-sdk
接下来，执行一些配置步骤：
- 在 Facebook for Developers 网站上，为您的应用获取应用 ID (App ID) 和应用密钥 (App Secret)。
- 启用 Facebook 登录机制：
- 在 Firebase 控制台中，打开 Auth 部分。
- 在登录方法标签页上，启用 Facebook 登录方法，并指定您之前从 Facebook 获得的应用 ID 和应用密钥。
- 然后，请务必转到 Facebook for Developers 网站，依次点击产品设置 (Product Settings) > Facebook 登录 (Facebook Login) 配置，然后在您的 Facebook 应用的设置页面中，确保您的 OAuth 重定向 URI（例如
my-app-12345.firebaseapp.com/__/auth/handler）出现在 OAuth 重定向 URI (OAuth redirect URIs) 列表中。
实现 Facebook 登录
要使用“传统版”Facebook 登录，请完成以下步骤。或者，您也可以使用 Facebook 受限登录，如下一部分所示。
- 按开发者文档中的说明操作，将 Facebook 登录集成到您的应用中。当初始化
FBSDKLoginButton对象时，设置一个委托 (delegate) 来接收登录和退出帐号事件。例如：在您的委托中，实现Swift
let loginButton = FBSDKLoginButton() loginButton.delegate = self
Objective-C
FBSDKLoginButton *loginButton = [[FBSDKLoginButton alloc] init]; loginButton.delegate = self;
didCompleteWithResult:error:。Swift
func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) { if let error = error { print(error.localizedDescription) return } // ... }Objective-C
- (void)loginButton:(FBSDKLoginButton *)loginButton didCompleteWithResult:(FBSDKLoginManagerLoginResult *)result error:(NSError *)error { if (error == nil) { // ... } else { NSLog(error.localizedDescription); } } - 在
UIApplicationDelegate中导入FirebaseCore模块，以及您的应用委托 (app delegate) 使用的所有其他 Firebase 模块。 例如，如需使用 Cloud Firestore 和 Authentication，请执行以下操作：Swift
import FirebaseCore import FirebaseFirestore import FirebaseAuth // ...Objective-C
@import FirebaseCore; @import FirebaseFirestore; @import FirebaseAuth; // ... - 配置一个
FirebaseApp共享实例（通常在应用的application:didFinishLaunchingWithOptions:方法中配置）：Swift
// Use Firebase library to configure APIs FirebaseApp.configure()
Objective-C
// Use Firebase library to configure APIs [FIRApp configure];
- 用户成功登录后，您可在
didCompleteWithResult:error:的实现代码中，为已登录的用户获取一个访问令牌，然后用该访问令牌换取 Firebase 凭据：Swift
let credential = FacebookAuthProvider .credential(withAccessToken: AccessToken.current!.tokenString)
Objective-C
FIRAuthCredential *credential = [FIRFacebookAuthProvider credentialWithAccessToken:[FBSDKAccessToken currentAccessToken].tokenString];
实现 Facebook 受限登录
要使用 Facebook 受限登录（而非“传统版”Facebook 登录），请完成以下步骤。
- 按开发者文档中的说明操作，将 Facebook 受限登录集成到您的应用中。
- 为每个登录请求生成唯一的随机字符串（“Nonce”），用来确保您获取的 ID 令牌专门用于响应您的应用的身份验证请求。此步骤对于防止重放攻击至关重要。
您可以使用
SecRandomCopyBytes(_:_:_)生成加密的安全 Nonce，如以下示例所示：您将通过登录请求发送 Nonce 的 SHA-256 哈希，Facebook 将在响应中原封不动地传递该值。为了验证响应，Firebase 会对原始 Nonce 进行哈希处理并将其与 Facebook 传递的值进行比较。Swift
// Adapted from https://auth0.com/docs/api-auth/tutorials/nonce#generate-a-cryptographically-random-nonce private func randomNonceString(length: Int = 32) -> String { precondition(length > 0) let charset: [Character] = Array("0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._") var result = "" var remainingLength = length while remainingLength > 0 { let randoms: [UInt8] = (0 ..< 16).map { _ in var random: UInt8 = 0 let errorCode = SecRandomCopyBytes(kSecRandomDefault, 1, &random) if errorCode != errSecSuccess { fatalError( "Unable to generate nonce. SecRandomCopyBytes failed with OSStatus \(errorCode)" ) } return random } randoms.forEach { random in if remainingLength == 0 { return } if random < charset.count { result.append(charset[Int(random)]) remainingLength -= 1 } } } return result }Objective-C
// Adapted from https://auth0.com/docs/api-auth/tutorials/nonce#generate-a-cryptographically-random-nonce - (NSString *)randomNonce:(NSInteger)length { NSAssert(length > 0, @"Expected nonce to have positive length"); NSString *characterSet = @"0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._"; NSMutableString *result = [NSMutableString string]; NSInteger remainingLength = length; while (remainingLength > 0) { NSMutableArray *randoms = [NSMutableArray arrayWithCapacity:16]; for (NSInteger i = 0; i < 16; i++) { uint8_t random = 0; int errorCode = SecRandomCopyBytes(kSecRandomDefault, 1, &random); NSAssert(errorCode == errSecSuccess, @"Unable to generate nonce: OSStatus %i", errorCode); [randoms addObject:@(random)]; } for (NSNumber *random in randoms) { if (remainingLength == 0) { break; } if (random.unsignedIntValue < characterSet.length) { unichar character = [characterSet characterAtIndex:random.unsignedIntValue]; [result appendFormat:@"%C", character]; remainingLength--; } } } return [result copy]; }Swift
@available(iOS 13, *) private func sha256(_ input: String) -> String { let inputData = Data(input.utf8) let hashedData = SHA256.hash(data: inputData) let hashString = hashedData.compactMap { String(format: "%02x", $0) }.joined() return hashString }Objective-C
- (NSString *)stringBySha256HashingString:(NSString *)input { const char *string = [input UTF8String]; unsigned char result[CC_SHA256_DIGEST_LENGTH]; CC_SHA256(string, (CC_LONG)strlen(string), result); NSMutableString *hashed = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH * 2]; for (NSInteger i = 0; i < CC_SHA256_DIGEST_LENGTH; i++) { [hashed appendFormat:@"%02x", result[i]]; } return hashed; } - 设置
FBSDKLoginButton时，请设置一个委托来接收登录和退出帐号事件，将跟踪模式设置为FBSDKLoginTrackingLimited，并附加一个 Nonce。例如：在您的委托中，实现Swift
func setupLoginButton() { let nonce = randomNonceString() currentNonce = nonce loginButton.delegate = self loginButton.loginTracking = .limited loginButton.nonce = sha256(nonce) }Objective-C
- (void)setupLoginButton { NSString *nonce = [self randomNonce:32]; self.currentNonce = nonce; self.loginButton.delegate = self; self.loginButton.loginTracking = FBSDKLoginTrackingLimited self.loginButton.nonce = [self stringBySha256HashingString:nonce]; }didCompleteWithResult:error:。Swift
func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) { if let error = error { print(error.localizedDescription) return } // ... }Objective-C
- (void)loginButton:(FBSDKLoginButton *)loginButton didCompleteWithResult:(FBSDKLoginManagerLoginResult *)result error:(NSError *)error { if (error == nil) { // ... } else { NSLog(error.localizedDescription); } } - 在
UIApplicationDelegate中导入FirebaseCore模块，以及您的应用委托 (app delegate) 使用的所有其他 Firebase 模块。 例如，如需使用 Cloud Firestore 和 Authentication，请执行以下操作：Swift
import FirebaseCore import FirebaseFirestore import FirebaseAuth // ...Objective-C
@import FirebaseCore; @import FirebaseFirestore; @import FirebaseAuth; // ... - 配置一个
FirebaseApp共享实例（通常在应用的application:didFinishLaunchingWithOptions:方法中配置）：Swift
// Use Firebase library to configure APIs FirebaseApp.configure()
Objective-C
// Use Firebase library to configure APIs [FIRApp configure];
- 用户成功登录之后，您可在
didCompleteWithResult:error:的实现代码中，使用 Facebook 响应中的 ID 令牌和未经哈希处理的 Nonce 来获取 Firebase 凭据：Swift
// Initialize a Firebase credential. let idTokenString = AuthenticationToken.current?.tokenString let nonce = currentNonce let credential = OAuthProvider.credential(withProviderID: "facebook.com", idToken: idTokenString!, rawNonce: nonce)Objective-C
// Initialize a Firebase credential. NSString *idTokenString = FBSDKAuthenticationToken.currentAuthenticationToken.tokenString; NSString *rawNonce = self.currentNonce; FIROAuthCredential *credential = [FIROAuthProvider credentialWithProviderID:@"facebook.com" IDToken:idTokenString rawNonce:rawNonce];
进行 Firebase 身份验证
最后，使用 Firebase 凭据进行 Firebase 身份验证：
Swift
Auth.auth().signIn(with: credential) { authResult, error in
if let error = error {
let authError = error as NSError
if isMFAEnabled, authError.code == AuthErrorCode.secondFactorRequired.rawValue {
// The user is a multi-factor user. Second factor challenge is required.
let resolver = authError
.userInfo[AuthErrorUserInfoMultiFactorResolverKey] as! MultiFactorResolver
var displayNameString = ""
for tmpFactorInfo in resolver.hints {
displayNameString += tmpFactorInfo.displayName ?? ""
displayNameString += " "
}
self.showTextInputPrompt(
withMessage: "Select factor to sign in\n\(displayNameString)",
completionBlock: { userPressedOK, displayName in
var selectedHint: PhoneMultiFactorInfo?
for tmpFactorInfo in resolver.hints {
if displayName == tmpFactorInfo.displayName {
selectedHint = tmpFactorInfo as? PhoneMultiFactorInfo
}
}
PhoneAuthProvider.provider()
.verifyPhoneNumber(with: selectedHint!, uiDelegate: nil,
multiFactorSession: resolver
.session) { verificationID, error in
if error != nil {
print(
"Multi factor start sign in failed. Error: \(error.debugDescription)"
)
} else {
self.showTextInputPrompt(
withMessage: "Verification code for \(selectedHint?.displayName ?? "")",
completionBlock: { userPressedOK, verificationCode in
let credential: PhoneAuthCredential? = PhoneAuthProvider.provider()
.credential(withVerificationID: verificationID!,
verificationCode: verificationCode!)
let assertion: MultiFactorAssertion? = PhoneMultiFactorGenerator
.assertion(with: credential!)
resolver.resolveSignIn(with: assertion!) { authResult, error in
if error != nil {
print(
"Multi factor finanlize sign in failed. Error: \(error.debugDescription)"
)
} else {
self.navigationController?.popViewController(animated: true)
}
}
}
)
}
}
}
)
} else {
self.showMessagePrompt(error.localizedDescription)
return
}
// ...
return
}
// User is signed in
// ...
}
Objective-C
[[FIRAuth auth] signInWithCredential:credential
completion:^(FIRAuthDataResult * _Nullable authResult,
NSError * _Nullable error) {
if (isMFAEnabled && error && error.code == FIRAuthErrorCodeSecondFactorRequired) {
FIRMultiFactorResolver *resolver = error.userInfo[FIRAuthErrorUserInfoMultiFactorResolverKey];
NSMutableString *displayNameString = [NSMutableString string];
for (FIRMultiFactorInfo *tmpFactorInfo in resolver.hints) {
[displayNameString appendString:tmpFactorInfo.displayName];
[displayNameString appendString:@" "];
}
[self showTextInputPromptWithMessage:[NSString stringWithFormat:@"Select factor to sign in\n%@", displayNameString]
completionBlock:^(BOOL userPressedOK, NSString *_Nullable displayName) {
FIRPhoneMultiFactorInfo* selectedHint;
for (FIRMultiFactorInfo *tmpFactorInfo in resolver.hints) {
if ([displayName isEqualToString:tmpFactorInfo.displayName]) {
selectedHint = (FIRPhoneMultiFactorInfo *)tmpFactorInfo;
}
}
[FIRPhoneAuthProvider.provider
verifyPhoneNumberWithMultiFactorInfo:selectedHint
UIDelegate:nil
multiFactorSession:resolver.session
completion:^(NSString * _Nullable verificationID, NSError * _Nullable error) {
if (error) {
[self showMessagePrompt:error.localizedDescription];
} else {
[self showTextInputPromptWithMessage:[NSString stringWithFormat:@"Verification code for %@", selectedHint.displayName]
completionBlock:^(BOOL userPressedOK, NSString *_Nullable verificationCode) {
FIRPhoneAuthCredential *credential =
[[FIRPhoneAuthProvider provider] credentialWithVerificationID:verificationID
verificationCode:verificationCode];
FIRMultiFactorAssertion *assertion = [FIRPhoneMultiFactorGenerator assertionWithCredential:credential];
[resolver resolveSignInWithAssertion:assertion completion:^(FIRAuthDataResult * _Nullable authResult, NSError * _Nullable error) {
if (error) {
[self showMessagePrompt:error.localizedDescription];
} else {
NSLog(@"Multi factor finanlize sign in succeeded.");
}
}];
}];
}
}];
}];
}
else if (error) {
// ...
return;
}
// User successfully signed in. Get user data from the FIRUser object
if (authResult == nil) { return; }
FIRUser *user = authResult.user;
// ...
}];
后续步骤
在用户首次登录后，系统会创建一个新的用户帐号，并将其与该用户登录时使用的凭据（即用户名和密码、手机号码或者身份验证提供方信息）相关联。此新帐号存储在您的 Firebase 项目中，无论用户采用何种方式登录，您项目中的每个应用都可以使用此帐号来识别用户。
在您的 Firebase Realtime Database 和 Cloud Storage 安全规则中，您可以从
auth变量获取已登录用户的唯一用户 ID，然后利用此 ID 来控制用户可以访问哪些数据。
您可以通过将多个身份验证提供方凭据与一个现有用户帐号关联，让用户可以使用多个身份验证提供方登录您的应用。
如需将用户退出登录，请调用 signOut:。
Swift
let firebaseAuth = Auth.auth()
do {
try firebaseAuth.signOut()
} catch let signOutError as NSError {
print("Error signing out: %@", signOutError)
}
Objective-C
NSError *signOutError;
BOOL status = [[FIRAuth auth] signOut:&signOutError];
if (!status) {
NSLog(@"Error signing out: %@", signOutError);
return;
}
您可能还需要为所有身份验证错误添加错误处理代码。请参阅处理错误。