Sign in with Twitter using iOS SDK https://dev.twitter.com/docs/ios/making-api-requests-slrequest

ios_twitter.m

- (void)testTwitter
{
    //  Step 0: Check that the user has local Twitter accounts
    BOOL isTwitterAvailable = [SLComposeViewController isAvailableForServiceType:SLServiceTypeTwitter];
    NSLog(@"isTwitterAvailable:%d", isTwitterAvailable);
    
    if (isTwitterAvailable) {
        
        //  Step 1:  Obtain access to the user's Twitter accounts
        ACAccountStore *accountStore = [[ACAccountStore alloc] init];
        ACAccountType *twitterAccountType = [accountStore accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
        
        [accountStore requestAccessToAccountsWithType:twitterAccountType options:nil completion:^(BOOL granted, NSError *error) {
            // Allow access to iOS Twitter account
            if (granted) {
                NSLog(@"granted!!");
                
                //  Step 2:  Create a request
                NSArray *twitterAccounts = [accountStore accountsWithAccountType:twitterAccountType];
                NSLog(@"twitterAccounts:%@", twitterAccounts);
                
                NSURL *url = [NSURL URLWithString:@"https://api.twitter.com/1.1/statuses/mentions_timeline.json"];
                NSDictionary *params = @{@"screen_name" : @"synboo",
                                         @"include_rts" : @"0",
                                         @"trim_user"   : @"1",
                                         @"count"       : @"50"};
                params = nil;
                SLRequest *request = [SLRequest requestForServiceType:SLServiceTypeTwitter
                                                        requestMethod:SLRequestMethodGET
                                                                  URL:url
                                                           parameters:params];
                //  Attach an account to the request
                [request setAccount:[twitterAccounts lastObject]];
                
                //  Step 3:  Execute the request
                [request performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
                    if (responseData) {
                        if (urlResponse.statusCode >= 200 && urlResponse.statusCode < 300) {
                            
                            NSError *jsonError;
                            NSDictionary *timelineData = [NSJSONSerialization JSONObjectWithData:responseData
                                                                                         options:NSJSONReadingAllowFragments
                                                                                           error:&jsonError];
                            if (timelineData) {
                                NSLog(@"Timeline Response: %@\n", timelineData);
                                for (NSDictionary *tweetStatus in timelineData) {
                                    NSLog(@"tweetStatus.text:%@", tweetStatus[@"text"]);
                                }
                            }
                            else {
                                // Our JSON deserialization went awry
                                [self alertMessage:[NSString stringWithFormat:@"JSON Error: %@", [jsonError localizedDescription]]];
                            }
                            
                        } else {
                            // The server did not respond ... were we rate-limited?
                            [self alertMessage:[NSString stringWithFormat:@"The response status code is %d", urlResponse.statusCode]];
                        }
                    } else {
                        [self alertMessage:@"Network error"];
                    }
                }];
                
            // Not allow
            } else {
                NSLog(@"not granted!!");
                // iOS Twitterアカウントがこのアプリを使うのを許可していない
                [self alertMessage:@"iOSのTwitterアカウント設定でこのアプリケーションを許可してください"];
            }
        }];
        
    } else {
        // iOS Twitterアカウント未設定
        [self alertMessage:@"iOSのTwitterアカウント連携をしてください"];
    }
}

- (void)alertMessage:(NSString *)message
{
    [[[UIAlertView alloc] initWithTitle:nil
                                message:message
                               delegate:self cancelButtonTitle:@"OK"
                      otherButtonTitles:nil, nil] show];
}