Why Google？

可能确实有人要问，为什么要在iOS上做谷歌的集成？
Sorry，目前来说除了项目需求之外，想不到特别好的理由，也是因为这个需求我才做了登录、Drive、Youtube的集成，个人感觉还是不轻松，觉得有必要分享一下，万一有人会用到呢？
而且，Google有很多好用的产品，万一将来逐渐解锁，我也是很愿意集成到自己的App里。

关于SSO单点登录

引用一篇文章，大致理解一下：
谁都能看懂的单点登录（SSO）实现方式（附源码

Google SSO

Google Sign-In

Pod

pod 'Google/SignIn'
不使用pod，手动也可以，只不过后续工作会有一些麻烦和不用，不赘述了。

配置App

Get Configuration File

• 通过上面连接快速注册一个App，填写名称和Bundle ID即可

Get Configuration File

• 点击Continue之后会让你选择该app支持的服务，这里我们只选择Sign-In就可以了

• 然后点击Download GoogleService-Info.plist
  进入Google API Console
  如图操作：

勾选iOS client for ..

• 将新合成的GoogleService-Info.plist拖入你的project

添加URL Schemes

将如下代码插入到你的info.plist中,YOUR_BUNDLE_ID和YOU_ REVERSED_CLIENT_ID 中的内容自行进行替换，两者都可以在GoogleService-Info.plist中找到

    <key>CFBundleURLTypes</key>
    <array>
        <dict>
            <key>CFBundleURLSchemes</key>
            <array>
                <string>YOUR_BUNDLE_ID</string>
            </array>
        </dict>
        <dict>
            <key>CFBundleURLSchemes</key>
            <array>
                <string>YOU_ REVERSED_CLIENT_ID </string>
            </array>
        </dict>
    </array>

Code

• 在AppleDelegate.m中，添加如下代码（其他部分省略）

@interface AppDelegate ()<GIDSignInDelegate>

@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    NSError* configureError;
    [[GGLContext sharedInstance] configureWithError: &configureError];
    NSAssert(!configureError, @"Error configuring Google services: %@", configureError);
    
    [GIDSignIn sharedInstance].delegate = self;
    return YES;
}

- (BOOL)application:(UIApplication *)app
            openURL:(NSURL *)url
            options:(NSDictionary *)options {
    return [[GIDSignIn sharedInstance] handleURL:url
                               sourceApplication:options[UIApplicationOpenURLOptionsSourceApplicationKey]
                                      annotation:options[UIApplicationOpenURLOptionsAnnotationKey]];
}

#pragma mark - GIDSignDelegate

- (void)signIn:(GIDSignIn *)signIn
didSignInForUser:(GIDGoogleUser *)user
     withError:(NSError *)error {
    // Perform any operations on signed in user here.
    NSString *userId = user.userID;                  // For client-side use only!
    NSString *idToken = user.authentication.idToken; // Safe to send to the server
    NSString *fullName = user.profile.name;
    NSString *givenName = user.profile.givenName;
    NSString *familyName = user.profile.familyName;
    NSString *email = user.profile.email;
    // ...
}

@end

• 登录按钮（以下为示例）

- (void)viewDidLoad {
    [super viewDidLoad];
    [GIDSignIn sharedInstance].uiDelegate = self;
    
    //Config sign in button
    GIDSignInButton *signButton = [[GIDSignInButton alloc] initWithFrame:CGRectMake(0, 0, 50, 50)];
    [self.view addSubview:signButton];
    signButton.center = self.view.center;
}

#pragma mark - GIDSignInUIDelegate
//该代理一般不用实现，除非自己对界面跳转或交互有一些需求
// Implement these methods only if the GIDSignInUIDelegate is not a subclass of
// UIViewController.

// Stop the UIActivityIndicatorView animation that was started when the user
// pressed the Sign In button
- (void)signInWillDispatch:(GIDSignIn *)signIn error:(NSError *)error {
  [myActivityIndicator stopAnimating];
}

// Present a view that prompts the user to sign in with Google
- (void)signIn:(GIDSignIn *)signIn
    presentViewController:(UIViewController *)viewController {
  [self presentViewController:viewController animated:YES completion:nil];
}

// Dismiss the "Sign in with Google" view
- (void)signIn:(GIDSignIn *)signIn
    dismissViewController:(UIViewController *)viewController {
  [self dismissViewControllerAnimated:YES completion:nil];
}

• 登出

调用
[[GIDSignIn sharedInstance] disconnect];
即可。

关于登出的两个方法

[[GIDSignIn sharedInstance] signOut];
//只做登出操作，不会清除keychain中保存的认证数据
[[GIDSignIn sharedInstance] disconnect];
//登出并断开，清除keychain中保存的认证数据。
//一般由用户的主动登出操作调用该方法。

Demo地址

FHGoogle-iOS-Client