某些 Google 服务(例如云端硬盘、Gmail 等)提供公共 API 您可以用它来创建应用,帮助用户在 Google Cloud 中 服务。要访问这些服务,应用必须实现 OAuth 2.0 客户端流程来获得用户同意,并获取访问令牌, 对 API 的访问权限。
您可以使用 Google 登录库,它为 来获取已登录用户的访问令牌。
准备工作
您必须完成基本的 Google 登录功能集成。
1. 查看已授予的范围
在调用 Google API 之前,请检查哪些范围已被使用
(使用 GIDGoogleUser
的 grantedScopes
属性授予您的应用):
Swift
let driveScope = "https://www.googleapis.com/auth/drive.readonly"
let grantedScopes = user.grantedScopes
if grantedScopes == nil || !grantedScopes!.contains(driveScope) {
// Request additional Drive scope.
}
Objective-C
NSString *driveScope = @"https://www.googleapis.com/auth/drive.readonly";
// Check if the user has granted the Drive scope
if (![user.grantedScopes containsObject:driveScope]) {
// request additional drive scope
}
根据用户是否已授予特定范围,您可以 为了支持特定的 互动
2. 请求附加范围
如果您需要请求其他作用域,请调用
addScopes:presentingViewController:completion
或
addScopes:presentingWindow:completion
,请求用户授予您的应用
额外访问权限。
例如,要请求以只读方式访问用户的云端硬盘文件,请执行以下操作:
Swift
let additionalScopes = ["https://www.googleapis.com/auth/drive.readonly"]
guard let currentUser = GIDSignIn.sharedInstance.currentUser else {
return ; /* Not signed in. */
}
currentUser.addScopes(additionalScopes, presenting: self) { signInResult, error in
guard error == nil else { return }
guard let signInResult = signInResult else { return }
// Check if the user granted access to the scopes you requested.
}
Objective-C
NSArray *additionalScopes = @[ @"https://www.googleapis.com/auth/drive.readonly" ];
GIDGoogleUser *currentUser = GIDSignIn.sharedInstance.currentUser;
[currentUser addScopes:additionalScopes
presentingViewController:self
completion:^(GIDSignInResult * _Nullable signInResult,
NSError * _Nullable error) {
if (error) { return; }
if (signInResult == nil) { return; }
// Check if the user granted access to the scopes you requested.
}];
3. 使用新令牌进行 API 调用
为了确保您的 Google API 调用始终具有未过期的访问令牌
因此,请将调用封装在 refreshTokensIfNeededWithCompletion:
块中:
Swift
currentUser.refreshTokensIfNeeded { user, error in
guard error == nil else { return }
guard let user = user else { return }
// Get the access token to attach it to a REST or gRPC request.
let accessToken = user.accessToken.tokenString
// Or, get an object that conforms to GTMFetcherAuthorizationProtocol for
// use with GTMAppAuth and the Google APIs client library.
let authorizer = user.fetcherAuthorizer()
}
Objective-C
[currentUser refreshTokensIfNeededWithCompletion:^(
GIDGoogleUser * _Nullable user,
NSError * _Nullable error) {
if (error) { return; }
if (user == nil) { return; }
// Get the access token to attach it to a REST or gRPC request.
NSString *accessToken = user.accessToken.tokenString;
// Or, get an object that conforms to GTMFetcherAuthorizationProtocol for
// use with GTMAppAuth and the Google APIs client library.
id<GTMFetcherAuthorizationProtocol> authorizer = [user fetcherAuthorizer];
}];
使用访问令牌来调用 API,方法是将访问令牌添加到
REST 或 gRPC 请求的标头 (Authorization: Bearer ACCESS_TOKEN
),
或者将提取程序授权程序与
Google API 客户端库。