Update Facebook token in iOS client from existing server-side cached token

gistfile1.m

[self.apiClient retrieveConnectedServicesWithSuccessBlock:^(NSDictionary *services) {
    NSArray *facebookTokens = services[@"facebook"];
    if (facebookTokens.count == 0) {
        return;
    }
    
    NSDictionary *mostRecentFacebookTokenDict = facebookTokens[0];

    NSNumber *refreshTimeNumber = mostRecentFacebookTokenDict[@"refreshTime"];
    NSDate *refreshDate = [NSDate dateWithTimeIntervalSince1970:[refreshTimeNumber doubleValue]];

    NSString *rawExpireDate = mostRecentFacebookTokenDict[@"expireTime"];
    NSDate *expireDate = [NSDate dateWithTimeIntervalSince1970:[rawExpireDate doubleValue]];

    NSNumber *loginTypeNumber = mostRecentFacebookTokenDict[@"loginType"];
    FBSessionLoginType loginType = [loginTypeNumber intValue];

    NSString *tokenString = mostRecentFacebookTokenDict[@"token"];
    NSArray *permissions = mostRecentFacebookTokenDict[@"permissions"];

    FBAccessTokenData *cachedTokenData = [FBAccessTokenData
                                          createTokenFromString:tokenString
                                          permissions:permissions
                                          expirationDate:expireDate
                                          loginType:loginType
                                          refreshDate:refreshDate];

    NSString *facebookAppID = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"FacebookAppID"];
    NSString *urlSchemeSuffix = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"FacebookUrlSchemeSuffix"];

    FBSession *session = [[FBSession alloc] initWithAppID:facebookAppID
                                              permissions:permissions
                                          defaultAudience:FBSessionDefaultAudienceNone
                                          urlSchemeSuffix:urlSchemeSuffix
                                       tokenCacheStrategy:[FBSessionTokenCachingStrategy nullCacheInstance]];
    [FBSession setActiveSession:session];

    [session openFromAccessTokenData:cachedTokenData completionHandler:^(FBSession *session, FBSessionState status, NSError *error) {
        [self onFacebookSession:session stateChanged:status error:error];

        [self.apiClient addFacebookAccessToken:FBSession.activeSession.accessTokenData withSuccessBlock:^(NSDictionary *facebookTokenInfo) {
            NSLog(@"Cached token data on server is old, added new facebook access token");
        } failureBlock:^(NSError *error) {
            NSLog(@"Cached token data on server is old, but couldn't upload new facebook access token: %@", error);
        }];
    }];

} failureBlock:^(NSError *error) {
    NSLog(@"Got error retrieving connected services: %@", error);
}];