Objective-c로 구글드라이브 연동하기(Google Drive api in objective-c)

클래스업(ClassUp)에 드롭박스를 연동했었는데 구글드라이브 또한 연동하게 되어 블로그에 글을 남겨볼까 한다.

드롭박스보다 조금 까다로웠기에 조금 자세히 알아볼 봐야할 필요가 있다.

순서

1. 기본적으로 Google Cloud Platform에 가입 후, 프로젝트 생성 후, API 및 서비스 사용 설정에서 Google Drive를 찾은 후 사용하기를 해야한다.
2. OAuth client ID를 생성해야 하기 때문에 디벨롭퍼 사이트로 가서 시키는대로 쭈욱 따라한다.
3. Google Drive api는 현재 v3인데, 여기로 가면 자세한 정보를 알 수 있다.

4. Podfile을 아래와 같이 수정한다.

    pod 'Google/SignIn'
    pod 'GoogleAPIClientForREST/Drive', '~> 1.2.1'
   

5. 샘플을 참고하면서 코딩하면 된다.

구조

1. 구글 드라이브의 사용권한을 가져온다.
2. 버튼을 클릭하면 구글 드라이브의 최상위에 존재하는 파일 및 폴더 목록을 가져와서 UITableView에 뿌린다.
3. 폴더를 클릭하면 해당 폴더 내의 파일 및 폴더 목록을 가져온다.
4. 파일을 클릭하면 해당 파일을 다운받아서 UIDocumentInteractionController을 이용하여 보여준다.
5. Google Docs 문서를 클릭할 경우 application/pdf로 export한 후에 pdf파일로 연다.

코딩

// Singleton 구현이 되어 있다고 가정한다.
// GTLRDriveService *service는 singleton.service로 표현한다.

// TestViewController.m

@implementation TestViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    //...

    singleton.service = [[GTLRDriveService alloc] init];
    // Turn on the library's shouldFetchNextPages feature to ensure that all items
    // are fetched.  This applies to queries which return an object derived from
    // GTLRCollectionObject.
    service.shouldFetchNextPages = YES;

    // Have the service object set tickets to retry temporary error conditions
    // automatically
    service.retryEnabled = YES;

    // 한번 로그인 후에는 다시 signIn할 필요가 없다.
    NSUserDefaults *userInfo = [NSUserDefaults standardUserDefaults];
    if([userInfo boolForKey:@"GoogleDrive"]) {
        [GIDSignIn sharedInstance].scopes = @[kGTLRAuthScopeDriveReadonly];
        [GIDSignIn sharedInstance].delegate = self;
        [GIDSignIn sharedInstance].uiDelegate = self;

        if([[GIDSignIn sharedInstance] hasAuthInKeychain]) {
            [[GIDSignIn sharedInstance] signInSilently];
        }
        else {
            [[GIDSignIn sharedInstance] signIn];
        }
    }
}

// 최초 로그인 시나 로그아웃 후에만 사용한다.
- (void)loginBtnPressed:(id)sender {
    [GIDSignIn sharedInstance].delegate = self;
    [GIDSignIn sharedInstance].uiDelegate = self;
    [GIDSignIn sharedInstance].scopes = @[kGTLRAuthScopeDriveReadonly];
    [[GIDSignIn sharedInstance] signIn];
}

- (void)signIn:(GIDSignIn *)signIn didSignInForUser:(GIDGoogleUser *)user
     withError:(NSError *)error {
    NSUserDefaults *userInfo = [NSUserDefaults standardUserDefaults];

    if(error) {
        singleton.service.authorizer = nil;
    }
    else {
        singleton.service.authorizer = user.authentication.fetcherAuthorizer;
        if([userInfo objectForKey:@"GoogleDrive"] == nil || ![userInfo boolForKey:@"GoogleDrive"]) {
            [userInfo setBool:YES forKey:@"GoogleDrive"];
            [userInfo synchronize];
        }
    }
}

- (void)signIn:(GIDSignIn *)signIn presentViewController:(UIViewController *)viewController
{
    [self presentViewController:viewController animated:YES completion:nil];
}

- (void)signIn:(GIDSignIn *)signIn dismissViewController:(UIViewController *)viewController {
    [viewController dismissViewControllerAnimated:YES completion:nil];
}

- (void)signOutBtnPressed:(id)sender {
    [[GIDSignIn sharedInstance] signOut];
    singleton.service.authorizer = nil;
    [userInfo setBool:NO forKey:@"GoogleDrive"];
    [userInfo synchronize];
}

@end

// ThirdPartyFileListViewController.m

@implementation ThirdPartyFileListViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Google Drive의 최상위는 root이다.
    if(self.searchPath == nil) {
        self.searchPath = @"root";
    }

    self.folderEntries = [[NSMutableArray alloc] init];

    self.fileLists.delegate = self;
    self.fileLists.dataSource = self;

    // ...
}

- (void)fetchFileList {
    __block GTLRServiceTicket *fileListTicket;

    GTLRDriveQuery_FilesList *query = [GTLRDriveQuery_FilesList query];

    // Because GTLRDrive_FileList is derived from GTLCollectionObject and the service
    // property shouldFetchNextPages is enabled, this may do multiple fetches to
    // retrieve all items in the file list.

    // Google APIs typically allow the fields returned to be limited by the "fields" property.
    // The Drive API uses the "fields" property differently by not sending most of the requested
    // resource's fields unless they are explicitly specified.
    query.fields = @"kind,nextPageToken,files(mimeType,id,kind,name,webViewLink,thumbnailLink,trashed)";
    query.q = [NSString stringWithFormat:@"trashed = false and '%@' IN parents", self.searchPath];

    fileListTicket = [singleton.service executeQuery:query
                                   completionHandler:^(GTLRServiceTicket *callbackTicket,
                                                       GTLRDrive_FileList *fileList,
                                                       NSError *callbackError) {
                                       // Callback
                                       fileListTicket = nil;
                                       if(callbackError != nil) {
                                           UIAlertController *alertController =
                                           [UIAlertController alertControllerWithTitle:@""
                                                                               message:callbackError.description
                                                                        preferredStyle:(UIAlertControllerStyle)UIAlertControllerStyleAlert];
                                           [alertController addAction:[UIAlertAction actionWithTitle:@"OK"
                                                                                               style:(UIAlertActionStyle)UIAlertActionStyleCancel
                                                                                             handler:nil]];
                                           [self presentViewController:alertController animated:YES completion:nil];
                                       }
                                       else {
                                           [self.folderEntries addObjectsFromArray:fileList.files];
                                           [self.fileLists reloadData];
                                       }
                                   }];

}

#pragma mark UITableView datasource method

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return [self.folderEntries count];
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    return 48;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"fileLists"];

    if(cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"fileLists"];
        cell.backgroundColor = [UIColor clearColor];
    }

    GTLRDrive_File *entry = [self.folderEntries objectAtIndex:[indexPath row]];
    cell.textLabel.text = entry.name;

    return cell;
}

#pragma mark UITableView delegate method

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    GTLRDrive_File *entry = [self.folderEntries objectAtIndex:[indexPath row]];
    if([@"application/vnd.google-apps.folder" isEqualToString:entry.mimeType]) {
        ThirdPartyFileListViewController *thirdPartyFileListController = [[ThirdPartyFileListViewController alloc] initWithNibName:@"ThirdPartyFileListViewController" bundle:nil];
        thirdPartyFileListController.thirdPartyType = self.thirdPartyType;
        thirdPartyFileListController.searchPath = entry.identifier;
        [self.navigationController pushViewController:thirdPartyFileListController animated:YES];
    }
    else {
        UIAlertController *popupMsg = [UIAlertController alertControllerWithTitle:nil message:nil preferredStyle:UIAlertControllerStyleActionSheet];
        __block __typeof__(popupMsg) blockAlert = popupMsg;
        UIAlertAction *link = [UIAlertAction actionWithTitle:NSLocalizedString(@"연결하기", nil) style:UIAlertActionStyleDefault handler:^(UIAlertAction * action) {
            [blockAlert dismissViewControllerAnimated:YES completion:nil];

        }];

        UIAlertAction *preview = [UIAlertAction actionWithTitle:NSLocalizedString(@"미리보기", nil) style:UIAlertActionStyleDefault handler:^(UIAlertAction * action) {
            [blockAlert dismissViewControllerAnimated:YES completion:nil];
            if([@"application/vnd.google-apps.document" isEqualToString:entry.mimeType]) {
                if(![self existPreviewFile:[NSString stringWithFormat:@"%@.pdf", entry.name]]) {
                    [self downloadDocsFileWithFile:entry];
                }
            }
            else {
                if(![self existPreviewFile:entry.name]) {
                    [self downloadFileWithPath:entry.identifier name:entry.name];
                }
            }
        }];

        UIAlertAction *cancel = [UIAlertAction actionWithTitle:NSLocalizedString(@"Cancel", nil) style:UIAlertActionStyleCancel handler:^(UIAlertAction * action) {
            [blockAlert dismissViewControllerAnimated:YES completion:nil];
            //            [popupMsg dismissViewControllerAnimated:YES completion:nil];
        }];

        [popupMsg addAction:link];
        [popupMsg addAction:preview];
        [popupMsg addAction:cancel];
        [self presentViewController:popupMsg animated:YES completion:^{
        }];
    }

    [self tableView:tableView didDeselectRowAtIndexPath:indexPath];
}

- (void)tableView:(UITableView *)tableView didDeselectRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    [cell setSelected:NO];
}

- (BOOL)existPreviewFile:(NSString *)name {
    NSString *filePath = [self.third_party_dir
                          stringByAppendingPathComponent:name];
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
        UIDocumentInteractionController* document = [UIDocumentInteractionController interactionControllerWithURL:[NSURL fileURLWithPath:filePath]];
        document.delegate = self;
        BOOL openResult = [document presentPreviewAnimated:YES];
        if(!openResult) {
            if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
                NSError *error = nil;
                [[NSFileManager defaultManager] removeItemAtPath:filePath error:&error];
            }

            [self showAlertControllerTitle:@"" message:@"Can not open this extension of file."];
        }
        return YES;
    }

    return NO;
}

- (void)downloadDocsFileWithFile:(GTLRDrive_File *)entry {
    NSString *filePath = [self.third_party_dir
                          stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.pdf", entry.name]];
    NSURL *destUrl = [NSURL fileURLWithPath:filePath];
    __block GTLRServiceTicket *fileListTicket;
    GTLRQuery *query = [GTLRDriveQuery_FilesExport queryForMediaWithFileId:entry.identifier mimeType:@"application/pdf"];

    //fileListTicket을 이용하여 중간에 취소할 수 있다.
    fileListTicket = [singleton.service executeQuery:query
                                   completionHandler:^(GTLRServiceTicket *callbackTicket,
                                                       GTLRDataObject *object,
                                                       NSError *callbackError) {
                                       [alert dismiss:YES];
                                       [alert removeFromSuperview];

                                       NSError *errorToReport = callbackError;
                                       NSError *writeError;
                                       if (callbackError == nil) {
                                           BOOL didSave = [object.data writeToURL:destUrl
                                                                          options:NSDataWritingAtomic
                                                                            error:&writeError];
                                           if (!didSave) {
                                               errorToReport = writeError;
                                           }
                                       }
                                       if (errorToReport == nil) {
                                           // Successfully saved the file.
                                           //
                                           // Since a downloadPath property was specified, the data argument is
                                           // nil, and the file data has been written to disk.
                                           //                    [self displayAlert:@"Downloaded"
                                           //                                format:@"%@", destinationURL.path];

                                           UIDocumentInteractionController* document = [UIDocumentInteractionController interactionControllerWithURL:destUrl];
                                           document.delegate = self;
                                           BOOL openResult = [document presentPreviewAnimated:YES];
                                           if(!openResult) {
                                               if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
                                                   NSError *error = nil;
                                                   [[NSFileManager defaultManager] removeItemAtPath:filePath error:&error];
                                               }

                                               [self showAlertControllerTitle:@"" message:@"Can not open this extension of file."];
                                           }


                                       } else {
                                           [self showAlertControllerTitle:@"Error Downloading File" message:[NSString stringWithFormat:@"%@", errorToReport]];

                                       }
                                   }];
}

- (void)downloadFileWithPath:(NSString *)path name:(NSString *)name {
    NSString *filePath = [self.third_party_dir
                          stringByAppendingPathComponent:name];

    __block GTLRServiceTicket *fileListTicket;
    GTLRQuery *query = [GTLRDriveQuery_FilesGet queryForMediaWithFileId:path];
    NSURL *destUrl = [NSURL fileURLWithPath:filePath];
    //fileListTicket을 이용하여 중간에 취소할 수 있다.
    fileListTicket = [singleton.service executeQuery:query
        completionHandler:^(GTLRServiceTicket *callbackTicket,
                            GTLRDataObject *object,
                            NSError *callbackError) {

            NSError *errorToReport = callbackError;
            NSError *writeError;
            if (callbackError == nil) {
                BOOL didSave = [object.data writeToURL:destUrl
                                               options:NSDataWritingAtomic
                                                 error:&writeError];
                if (!didSave) {
                    errorToReport = writeError;
                }
            }
            if (errorToReport == nil) {
                // Successfully saved the file.
                //
                // Since a downloadPath property was specified, the data argument is
                // nil, and the file data has been written to disk.
                UIDocumentInteractionController* document = [UIDocumentInteractionController interactionControllerWithURL:destUrl];
                document.delegate = self;
                BOOL openResult = [document presentPreviewAnimated:YES];
                if(!openResult) {
                    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
                        NSError *error = nil;
                        [[NSFileManager defaultManager] removeItemAtPath:filePath error:&error];
                    }

                    [self showAlertControllerTitle:@"" message:@"Can not open this extension of file."];
                }


            } else {
                NSLog(@"Error Downloading File : %@", errorToReport);
            }
        }];
}

- (UIViewController *) documentInteractionControllerViewControllerForPreview: (UIDocumentInteractionController *) controller {
    return self;
}

- (void)documentInteractionControllerWillBeginPreview:(UIDocumentInteractionController *)controller {
    AVURLAsset *avUrl = [AVURLAsset assetWithURL:controller.URL];
    CMTime time = [avUrl duration];
    time = CMTimeMultiplyByRatio(time, 1, 1000);
    float seconds = roundf(time.value/(float)(time.timescale/1000.0));

    CFStringRef UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)controller.URL.pathExtension, NULL);

    if(UTTypeConformsTo(UTI, kUTTypeMovie) && seconds > 60.0f) {
        NSLog(@"영상의 미리보기는 1분을 넘을 수 없음.")
    }
}

- (void)documentInteractionController:(UIDocumentInteractionController *)controller didEndSendingToApplication:(NSString *)application {
    NSLog(@"전송 완료");
}
@end

복잡해 보이지만 위와 같이 구현할 수 있다.

1. mimeType은 여기에서 자세히 알아볼 수 있다.
2. 대부분 샘플에 존재하는 코드이며 나한테 맞게 바꾸었을 뿐이므로 자세한 것은 샘플을 참고하는 것이 좋다.
3. third_party_dir은 파일을 다운받았을 때, 저장할 저장소를 뜻한다. 앱 내부 저장소를 지우는 부분 구현도 당연히 필요하다.

다음은 Android에 드롭박스(DropBox) 및 구글 드라이브(Google Drive)를 연동한 내용을 올리려고 한다.