LetMeAuth-demo.m

- (void)performVKLogin
{
	@weakify(self);

	id conf = @{
				LMAVkontakteSDKClientId : __YOUR_APP_ID__,
				LMAVkontakteSDKScope : @[ VK_PER_WALL, VK_PER_STATUS, VK_PER_EMAIL ],
				LMAVkontakteSDKRevokeAccess : @NO,
				LMAVkontakteSDKForceOAuth : @YES,
				LMAVkontakteSDKAuthorizeInApp : @YES
				};

	// authController живёт в AppDelegate
	id<LMARequest> request = [authController authorizeWithProvider:@"vkontakte" configuration:conf completionHandler:^(NSDictionary *credential, NSError *error) {
		if (error)
		{
			@strongify(self);
			[self showError:error title:@"Ошибка входа"];
			return;
		}

		if (!credential)
		{
			NSLog(@"User cancelled login!");
			return;
		}

		NSLog(@"Finished vkontakte auth: %@", credential);
		// тут сохраняю credential

		[VKSdk wakeUpSession];
		VKRequest *req = [[VKApi users] get];
		[req executeWithResultBlock:^(VKResponse *response) {
			@strongify(self);

			NSString *firstName = response.json[0][@"first_name"];
			NSString *lastName = response.json[0][@"last_name"];
			NSString *fullName = [NSString stringWithFormat:@"%@ %@", firstName, lastName];
			NSString *email = credential[@"email"]

			// тут сохраняю данные юзера

			[self showGreetings:fullName];
		} errorBlock:^(NSError *reqError) {
			@strongify(self);
			[self showError:reqError title:@"Ошибка запрса данных"];
		}];
	}];

	[request start];
}


- (void)performTwitterLogin
{
	@weakify(self);

	id conf = @{
				LMATwitterSTConsumerKey : __YOUR_APP_KEY__,
				LMATwitterSTConsumerSecret : __YOUR_APP_SECRET__,
				LMATwitterSTCallbackURL : @"__YOUR_APP_SCHEME__://twitter"
				};

	id<LMARequest> request = [authController authorizeWithProvider:@"twitter" configuration:conf completionHandler:^(NSDictionary *credential, NSError *error) {
		if (error)
		{
			@strongify(self);
			[self showError:error title:@"Ошибка входа"];
			return;
		}

		if (!credential)
		{
			NSLog(@"User cancelled login!");
			return;
		}

		NSLog(@"Finished twitter auth: %@", credential);
		// опять сохраняю credential

		self.twitter = [STTwitterAPI twitterAPIWithOAuthConsumerKey:__YOUR_APP_KEY__ consumerSecret:__YOUR_APP_SECRET__ oauthToken:credential[@"oauth_token"] oauthTokenSecret:credential[@"oauth_token_secret"]];

		[self.twitter getUsersShowForUserID:nil orScreenName:credential[@"screen_name"] includeEntities:nil successBlock:^(NSDictionary *user) {
			NSString *name = user[@"name"];
			NSString *screenName = user[@"screen_name"];
			// сохраняю данные юзера

			@strongify(self);
			[self showGreetings:name];
		} errorBlock:^(NSError *getError) {
			@strongify(self);
			[self showError:getError title:@"Ошибка запроса данных"];
		}];
	}];

	[request start];
}

- (void)performGooglePlusLogin
{
	@weakify(self);

	id conf = @{
				LMAGooglePlusSDKClientId : __YOUR_APP_ID__,
				LMAGooglePlusSDKScope : @[ kGTLAuthScopePlusLogin, kGTLAuthScopePlusMe, kGTLAuthScopePlusUserinfoEmail, kGTLAuthScopePlusUserinfoProfile ]
				};

	id<LMARequest> request = [authController authorizeWithProvider:@"googleplus" configuration:conf completionHandler:^(NSDictionary *credential, NSError *error) {
		if (error)
		{
			@strongify(self);
			[self showError:error title:@"Ошибка входа"];
			return;
		}

		if (!credential)
		{
			NSLog(@"User cancelled login!");
			return;
		}

		// сохраняю credential

		GTLServicePlus *plusService = [GTLServicePlus new];
		[plusService setAuthorizer:[MYGooglePlusAuth new]];

		GTLQueryPlus *query = [GTLQueryPlus queryForPeopleGetWithUserId:@"me"];

		[plusService executeQuery:query completionHandler:^(GTLServiceTicket *__unused ticket, GTLPlusPerson *person, NSError *queryError) {
			if (queryError)
			{
				[self showError:queryError title:@"Ошибка запроса данных"];
			}
			else
			{
				GTLPlusPersonEmailsItem *emailItem = person.emails[0];
				NSString *displayName = person.displayName;
				NSString *email = emailItem.value;
				NSString *profileUrl = person.url;
				// сохраняю данные

				@strongify(self);
				[self showGreetings:person.displayName];
			}
		}];
	}];

	[request start];
}


- (void)performFacebookLogin
{
	@weakify(self);

	id conf = @{
				LMAFacebookSDKAppId : __YOUR_APP_ID__,
				LMAFacebookSDKPermissions : @[ @"public_profile", @"email", @"user_friends" ],
				LMAFacebookSDKURLSchemeSuffix : @"",
				LMAFacebookSDKAudience : LMAFacebookSDKAudienceEveryone
				};

	id<LMARequest> request = [authController authorizeWithProvider:@"facebook" configuration:conf completionHandler:^(NSDictionary *credential, NSError *error) {
		if (error)
		{
			@strongify(self);
			[self showError:error title:@"Ошибка входа"];
			return;
		}

		if (!credential)
		{
			NSLog(@"User cancelled login!");
			return;
		}

		// сохраняю credential

		id completionBlock = ^(FBSession *__unused session, FBSessionState __unused status, NSError *__unused openError) {
			if (openError)
			{
				@strongify(self);
				[self showError:openError title:@"Ошибка запроса данных"];
				return;
			}

			[[FBRequest requestForMe] startWithCompletionHandler:^(FBRequestConnection *__unused connection, NSDictionary<FBGraphUser> *user, NSError *reqError) {
				@strongify(self);
				if (!reqError)
				{
					NSString *name = user.name;
					NSString *email = user[@"email"];
					
					// сохраняю данные
					
					[self showGreetings:user.name];
				}
				else
				{
					[self showError:reqError title:@"Ошибка запроса данных"];
				}
			}];
		};

		if (FBSession.activeSession.state == FBSessionStateCreatedTokenLoaded)
		{
			[FBSession.activeSession openWithCompletionHandler:completionBlock];
		}
		else
		{
			FBAccessTokenData *td = [FBAccessTokenData createTokenFromString:credential[@"access_token"]
																 permissions:credential[@"scope"]
														 declinedPermissions:@[]
															  expirationDate:credential[@"expires_at"]
																   loginType:FBSessionLoginTypeNone
																 refreshDate:nil
													  permissionsRefreshDate:nil
																	   appID:nil
																	  userID:nil];
			[FBSession.activeSession openFromAccessTokenData:td completionHandler:completionBlock];
		}
	}];

	[request start];
}

// класс MYGooglePlusAuth — для авторизации через G+

@interface MYGooglePlusAuth : NSObject <GTMFetcherAuthorizationProtocol>

@end

@interface MYGooglePlusAuth ()

@property (nonatomic, strong) NSString *accessToken;

@end

@implementation MYGooglePlusAuth

@synthesize userEmail;

- (instancetype)init
{
	self = [super init];
	if (self)
	{
		self.accessToken = [[MYSettings sharedInstance] loginCredentials][@"googleplus"][@"access_token"];
	}
	return self;
}

#pragma mark - GTMFetcherAuthorizationProtocol

- (void)authorizeRequest:(NSMutableURLRequest *)request delegate:(id)delegate didFinishSelector:(SEL)sel
{
	if (request)
	{
		NSString *value = [NSString stringWithFormat:@"%s %@", GTM_OAUTH2_BEARER, self.accessToken];
		[request setValue:value forHTTPHeaderField:@"Authorization"];
	}

	NSMethodSignature *sig = [delegate methodSignatureForSelector:sel];
	NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:sig];
	[invocation setSelector:sel];
	[invocation setTarget:delegate];
	[invocation setArgument:(__bridge void *)(self) atIndex:2];
	[invocation setArgument:&request atIndex:3];
	[invocation invoke];
}

- (void)authorizeRequest:(NSMutableURLRequest *)request completionHandler:(void (^)(NSError *error))__unused handler
{
	if (request)
	{
		NSString *value = [NSString stringWithFormat:@"%@ %@", @"Bearer", self.accessToken];
		[request setValue:value forHTTPHeaderField:@"Authorization"];
	}
}

- (BOOL)isAuthorizedRequest:(NSURLRequest *)__unused request
{
	return NO;
}

- (void)stopAuthorization
{
}

- (void)stopAuthorizationForRequest:(NSURLRequest *)__unused request
{
}

- (BOOL)isAuthorizingRequest:(NSURLRequest *)__unused request
{
	return YES;
}

@end