JavaV2NIMStorageScene addCustomStorageScene(String sceneName, long expireTime);

Objective-C- (void)addCustomStorageScene:(NSString *)sceneName expireTime:(NSUInteger)expireTime;

C++virtual void addCustomStorageScene(nstd::string sceneName, uint64_t expireTime) = 0;

TypeScriptaddCustomStorageScene(sceneName: string, expireTime: number): V2NIMStorageScene

TypeScriptaddCustomStorageScene(sceneName: string, expireTime: number): V2NIMStorageScen

JavaV2NIMStorageService v2StorageService = NIMClient.getService(V2NIMStorageService.class);
v2StorageService.addCustomStorageScene(sceneName, expireTime);

Objective-C[[[NIMSDK sharedSDK] v2StorageService] addCustomStorageScene:@"scene_name" expireTime:1000];

C++storageService.addCustomStorageScene("customScene", 0); // never expire

TypeScriptnim.V2NIMStorageService.addCustomStorageScene("nim", 86400)

TypeScriptnim.storageService.addCustomStorageScene("nim", 86400)

V2NIMStorageScene

无。

JavaList<V2NIMStorageScene> getStorageSceneList();

Objective-C- (NSArray<V2NIMStorageScene *> *)getStorageSceneList;

C++virtual nstd::vector<V2NIMStorageScene> getStorageSceneList() = 0;

TypeScriptgetStorageSceneList(): V2NIMStorageScene[]

TypeScriptgetStorageSceneList(): V2NIMStorageScene[]

JavaV2NIMStorageService v2StorageService = NIMClient.getService(V2NIMStorageService.class);
List<V2NIMStorageScene> storageSceneList = v2StorageService.getStorageSceneList();

Objective-C[[[NIMSDK sharedSDK] v2StorageService] getStorageSceneList];

C++auto sceneList = storageService.getStorageSceneList();

TypeScriptconst sceneList = nim.V2NIMStorageService.getStorageSceneList()

TypeScriptconst sceneList = nim.storageService.getStorageSceneList()

JavaV2NIMUploadFileTask createUploadFileTask(V2NIMUploadFileParams params);

Objective-C- (V2NIMUploadFileTask *)createUploadFileTask:(V2NIMUploadFileParams *)fileParams;

C++virtual V2NIMUploadFileTask createUploadFileTask(V2NIMUploadFileParams fileParams) = 0;

TypeScriptcreateUploadFileTask(fileParams: V2NIMUploadFileParams): V2NIMUploadFileTask

TypeScriptcreateUploadFileTask(fileParams: V2NIMUploadFileParams): V2NIMUploadFileTask

JavaV2NIMStorageService v2StorageService = NIMClient.getService(V2NIMStorageService.class);
V2NIMUploadFileParams params = new V2NIMUploadFileParams("filePath")
V2NIMUploadFileTask uploadFileTask = v2StorageService.createUploadFileTask(params);

Objective-CV2NIMUploadFileParams *fileParams = [[V2NIMUploadFileParams alloc] init];
fileParams.filePath = @"filePath";
[[[NIMSDK sharedSDK] v2StorageService] createUploadFileTask:fileParams];

C++V2NIMUploadFileParams fileParams;
fileParams.filePath = "~/test.txt";
fileParams.name = "hello.txt";
fileParams.scene = "customScene";
auto uploadTask = storageService.createUploadFileTask(fileParams);

TypeScriptconst task = nim.V2NIMStorageService.createUploadFileTask({
    fileObj: document.getElementById('input-id').files[0]
}})

TypeScriptconst params:V2NIMUploadFileParams = {
    filePath: '文件沙盒路径',
    sceneName: '场景名'
} as V2NIMUploadFileParams

const task = nim.storageService.createUploadFileTask(params)

Javavoid uploadFile(V2NIMUploadFileTask fileTask, V2NIMSuccessCallback<String> success,
    V2NIMFailureCallback failure,
    V2NIMProgressCallback progress);

Objective-C- (void)uploadFile:(V2NIMUploadFileTask *)fileTask
           success:(V2NIMFileUploadSuccess)success
           failure:(V2NIMFileUploadFailure)failure
          progress:(V2NIMFileUploadProgress)progress;

C++virtual void uploadFile(V2NIMUploadFileTask fileTask,
    V2NIMSuccessCallback<nstd::string> success,
    V2NIMFailureCallback failure,
    V2NIMProgressCallback progress) = 0;

TypeScriptuploadFile(fileTask: V2NIMUploadFileTask, progress: V2NIMProgressCallback): Promise<string>

TypeScriptuploadFile(fileTask: V2NIMUploadFileTask, progress: V2NIMProgressCallback): Promise<string>

JavaV2NIMStorageService v2StorageService = NIMClient.getService(V2NIMStorageService.class);
v2StorageService.uploadFile(task, (V2NIMSuccessCallback<String>) s -> {
    // 上传成功
}, (V2NIMFailureCallback) error -> {
    // 上传失败
}, (V2NIMProgressCallback) progress -> {
    // 上传进度
});

Objective-C[[[NIMSDK sharedSDK] v2StorageService] uploadFile:fileTask success:^(NSString * _Nonnull urlString) {
        // 上传成功
    } failure:^(V2NIMError * _Nonnull error) {
        // 上传失败
    } progress:^(float progress) {
         // 上传进度
    }];

C++V2NIMUploadFileParams fileParams;
fileParams.filePath = "~/test.txt";
fileParams.name = "hello.txt";
fileParams.scene = "customScene";
auto uploadTask = storageService.createUploadFileTask(fileParams);
storageService.uploadFile(
    uploadTask,
    [](nstd::string url) {
        // upload file succeeded
    },
    [](V2NIMError error) {
        // upload file failed, handle error
    },
    [](uint32_t progress) {
        // upload progress
    });

TypeScriptnim.V2NIMStorageService.uploadFile(task, function onProgress(progress) {
 console.log('uploadFile progress: ', progress)
})

TypeScriptnim.storageService.uploadFile(task, function onProgress(progress) {
 console.log('uploadFile progress: ', progress)
})

无返回值。

Promise<string> 文件 URL 地址

• 请求成功，返回 V2NIMSuccessCallback 回调，包含文件 URL 地址。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储相关错误码。

• 请求成功，返回 V2NIMFileUploadSuccess 回调，可自定义设置。
• 请求失败，返回 V2NIMFileUploadFailure 回调，可自定义设置。

无。

Javavoid cancelUploadFile(V2NIMUploadFileTask fileTask, V2NIMSuccessCallback<Void> success,
    V2NIMFailureCallback failure);

Objective-C- (void)cancelUploadFile:(V2NIMUploadFileTask *)fileTask
                 success:(V2NIMSuccessCallback)success
                 failure:(V2NIMFailureCallback)failure;

C++virtual void cancelUploadFile(V2NIMUploadFileTask fileTask, V2NIMSuccessCallback<void> success, V2NIMFailureCallback failure) = 0;

TypeScriptcancelUploadFile(fileTask: V2NIMUploadFileTask): Promise<void>

TypeScriptcancelUploadFile(fileTask: V2NIMUploadFileTask): Promise<void>

JavaV2NIMStorageService v2StorageService = NIMClient.getService(V2NIMStorageService.class);
v2StorageService.cancelUploadFile(task, (V2NIMSuccessCallback<Void>) s -> {
    // 取消成功
}, (V2NIMFailureCallback) error -> {
    // 取消失败
});

Objective-C[[[NIMSDK sharedSDK] v2StorageService] cancelUploadFile:fileTask success:^{
        //取消成功
    } failure:^(V2NIMError * _Nonnull error) {
        //取消失败
    }];

C++V2NIMUploadFileTask fileTask;
// uploadFile
// ...
storageService.cancelUploadFile(
    fileTask,
    []() {
        // cancel upload file succeeded
    },
    [](V2NIMError error) {
        // cancel upload file failed, handle error
    });

TypeScriptnim.V2NIMStorageService.cancelUploadFile(task)

TypeScriptnim.storageService.cancelUploadFile(task)

无返回值。

Promise<void>

• 请求成功，返回 V2NIMSuccessCallback 回调。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储相关错误码。

无。

Javavoid downloadFile(String url, String filePath, V2NIMSuccessCallback<String> success,
    V2NIMFailureCallback failure, V2NIMProgressCallback progress);

Objective-C- (void)downloadFile:(NSString *)url
            filePath:(NSString *)filePath
             success:(V2NIMSuccessCallback)success
             failure:(V2NIMFailureCallback)failure
            progress:(nullable V2NIMProgressCallback)progress;

C++virtual void v2::V2NIMStorageService::downloadFile    ("   const nstd::string &     url,
                                                        const nstd::string &     savePath,
                                                        V2NIMSuccessCallback< nstd::string >     success,
                                                        V2NIMFailureCallback     failure,
                                                        V2NIMProgressCallback     progress )

JavaString url = "https://www.abc.com/ttt.txt";
// 设置文件存储位置
String filePath = "xxx/ttt.txt";
NIMClient.getService(V2NIMStorageService.class).downloadFile(url, filePath, new V2NIMSuccessCallback<String>() {
    @Override
    public void onSuccess(String filePath) {
        // 下载成功
    }
}, new V2NIMFailureCallback() {
    @Override
    public void onFailure(V2NIMError error) {
        // 下载失败
    }
}, new V2NIMProgressCallback() {
    @Override
    public void onProgress(int progress) {
        // 下载进度
    }
});

Objective-C// 按需配置远程目录
NSString *url = @"https://www.abc.com/ttt.txt";
// 按需配置存储目录
NSString *filePath = @"Document/ttt.txt";
[[NIMSDK sharedSDK].v2StorageService downloadFile:url filePath:filePath success:^() {
    // 成功回调
} failure:^(V2NIMError *error) {
    // 失败回调
} progress:^(NSUInteger progress) {
    // 进度回调
}];

C++storageService.downloadFile(
    "https://example.com/test.txt",
    "~/test.txt",
    [](const nstd::string& url) {
        // download file succeeded
    },
    [](V2NIMError error) {
        // download file failed, handle error
    },
    [](uint32_t progress) {
        // download progress
    });

Javavoid shortUrlToLong(String url, V2NIMSuccessCallback<String> success,
    V2NIMFailureCallback failure);

Objective-C- (void)shortUrlToLong:(NSString *)url
               success:(V2NIMShortUrlToLongSuccess)success
               failure:(V2NIMFailureCallback)failure;

C++virtual void v2::V2NIMStorageService::shortUrlToLong    ("   const nstd::string &     url,
                                                            V2NIMSuccessCallback< nstd::string >     success,
                                                            V2NIMFailureCallback     failure )

TypeScriptshortUrlToLong(url: string): Promise<string>

JavaString shortUrl = "https://s.netease.im/safe/AAAAAAAAAAAAAAAAAAAAAAAAAAA?_im_url=1";
NIMClient.getService(V2NIMStorageService.class).shortUrlToLong(shortUrl, new V2NIMSuccessCallback<String>() {
    @Override
    public void onSuccess(String longUrl) {
        // 转换成功
    }
}, new V2NIMFailureCallback() {
    @Override
    public void onFailure(V2NIMError error) {
        // 转换失败
    }
});

Objective-C// 按需传入短链
NSString *shortUrl = @"https://s.netease.im/safe/AAAAAAAAAAAAAAAAAAAAAAAAAAA?_im_url=1";
[[NIMSDK sharedSDK].v2StorageService shortUrlToLong:shortUrl success:^(NSString *url) {
    // 成功回调
} failure:^(V2NIMError *error) {
    // 失败回调
}];

C++storageService.shortUrlToLong("https://example.com/short?_im_url=1", [](nstd::string url) {
    // short url to long succeeded
}, [](V2NIMError error) {
    // short url to long failed, handle error
});

TypeScriptvar shortUrl = "https://s.netease.im/safe/AAAAAAAAAAAAAAAAAAAAAAAAAAA?_im_url=1";
var originUrl = await nim.V2NIMStorageService.shortUrlToLong(shortUrl)

无。

Promise<string>

• 请求成功，返回 V2NIMSuccessCallback 回调。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储相关错误码。

• 请求成功，返回 V2NIMShortUrlToLongSuccess 回调，可自定义设置。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储相关错误码。

无。

Javapublic static String imageThumbUrl(String url,int thumbSize)

Objective-C+ (NSString *)imageThumbUrl:(NSString *)url
                  thumbSize:(NSInteger)thumbSize;

C++nstd::string v2::V2NIMStorageUtil::imageThumbUrl    ("   const nstd::string &     url,
                                                        int32_t     thumbSize )

TypeScriptimageThumbUrl(url: string, thumbSize: number): string

TypeScriptimageThumbUrl(url: string, thumbSize: number): string

JavaString url = "http://xxx.com/xxx.jpg";
int thumbSize = 100;
String imageThumbUrl = V2NIMStorageUtil.imageThumbUrl(url, thumbSize);

Objective-C- (void)imageThumbUrl
{
    V2NIMMessage *message = nil; // message
    V2NIMMessageImageAttachment *attachment = nil; // image attachment
    if ([message.attachment isKindOfClass:V2NIMMessageImageAttachment.class]) {
        attachment = (V2NIMMessageImageAttachment *)(message.attachment);
    }
    if (attachment) {
        NSInteger size = 100; // screen size
        size *= UIScreen.mainScreen.scale;
        // keep aspect ratio and width or height > size
        NSString *thumbUrl = [V2NIMStorageUtil imageThumbUrl:attachment.url thumbSize:size];
    }
}

C++auto thumbURL= V2NIMStorageUtil::imageThumbUrl("image_url", 100);

TypeScriptconst url = nim.V2NIMStorageUtil.imageThumbUrl("https://host/path", 80)

TypeScriptconst url = nim.storageUtil.imageThumbUrl("https://host/path", 80)

Javavoid getImageThumbUrl(V2NIMMessageAttachment attachment,
                    V2NIMSize thumbSize,
                    V2NIMSuccessCallback<V2NIMGetMediaResourceInfoResult> success,
                    V2NIMFailureCallback failure);

Objective-C- (void)getImageThumbUrl:(V2NIMMessageAttachment *)attachment
               thumbSize:(V2NIMSize *)thumbSize
                 success:(V2NIMGetImageThumbUrlSuccess)success
                 failure:(V2NIMFailureCallback)failure;

C++virtual void v2::V2NIMStorageService::getImageThumbUrl    (
                const nstd::shared_ptr< V2NIMMessageAttachment > &     attachment,
                const nstd::optional< V2NIMSize > & thumbSize,
                const V2NIMSuccessCallback< const V2NIMGetMediaResourceInfoResult & > & success,
                const V2NIMFailureCallback &     failure
)

TypeScriptgetImageThumbUrl(attachment: V2NIMMessageAttachment, thumbSize: V2NIMSize): Promise<V2NIMGetMediaResourceInfoResult>

Java// 从消息中获取附件，只能使用 V2NIMMessageImageAttachment
V2NIMMessageAttachment attachment = message.getAttachment();
// 指定图片大小。0 表示该维度不限制
V2NIMSize thumbSize = new V2NIMSize();
thumbSize.setWidth(100);
thumbSize.setHeight(0);

NIMClient.getService(V2NIMStorageService.class).getImageThumbUrl(attachment, thumbSize, s -> {
    // 获取成功
}, f -> {
    // 获取失败
});

Objective-C// 从消息中获取附件，只能使用 V2NIMMessageImageAttachment
V2NIMMessageAttachment *attachment = message.attachment;
// 指定图片大小。0 表示该维度不限制
V2NIMSize *thumbSize = [[V2NIMSize alloc] initWithWidth:100 height:0];

[[NIMSDK sharedSDK].v2StorageService getImageThumbUrl:attachment thumbSize:thumbSize success:^(V2NIMGetMediaResourceInfoResult *result) {
    // 获取成功
} failure:^(V2NIMError *error) {
    // 获取失败
}];

C++storageService.getImageThumbUrl(attachment, V2NIMSize(150, 150), [](const V2NIMGetMediaResourceInfoResult& result) {
        // get image thumb url succeeded
    }, [](V2NIMError error) {
        // get image thumb url failed, handle error
    });

TypeScript/**
   * 生成图片缩略链接
   *
   * ESM 模式时，需要动态引入 V2NIMStorageUtil 后使用:
   * NIM.registerService(V2NIMStorageUtil, 'V2NIMStorageUtil')
   *
   * 使用示例: nim.V2NIMStorageService.getImageThumbUrl(attachment, { width: 100, height: 100 })
   */
  getImageThumbUrl(attachment: V2NIMMessageAttachment, thumbSize: V2NIMSize): Promise<V2NIMGetMediaResourceInfoResult>

无。

Promise<V2NIMGetMediaResourceInfoResult>

• 请求成功，返回 V2NIMSuccessCallback<V2NIMGetMediaResourceInfoResult> 回调，包含附件下载路径。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储服务相关错误码。

• 请求成功，返回 V2NIMGetImageThumbUrlSuccess 回调，包含附件下载路径。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储服务相关错误码。

无。

Javapublic static String videoCoverUrl(String url,int offset)

Objective-C+ (NSString *)videoCoverUrl:(NSString *)url
                     offset:(NSInteger)offset;

C++nstd::string v2::V2NIMStorageUtil::videoCoverUrl ("const nstd::string & url,
                                                        int32_t offset,
                                                        int32_t thumbSize,
                                                        const nstd::string & type )

TypeScriptvideoCoverUrl(url: string, offset: number): string

TypeScriptvideoCoverUrl(url: string, offset: number): string

JavaString url = "http://xxx.com/xxx.jpg";
int offset = 0;
String videoCoverUrl = V2NIMStorageUtil.videoCoverUrl(url, offset);

Objective-C- (void)videoCoverUrl
{
    V2NIMMessage *message = nil; // message
    V2NIMMessageVideoAttachment *attachment = nil; // video attachment
    if ([message.attachment isKindOfClass:V2NIMMessageVideoAttachment.class]) {
        attachment = (V2NIMMessageVideoAttachment *)(message.attachment);
    }
    if (attachment) {
        NSInteger offset = 0; // start of video
        NSString *coverUrl = [V2NIMStorageUtil videoCoverUrl:attachment.url offset:offset];
    }
}

C++auto coverURL = V2NIMStorageUtil::videoCoverUrl("video_url", 0, 150, "png");

TypeScriptconst url = nim.V2NIMStorageUtil.videoCoverUrl("https://host/path", 0)

TypeScriptconst url = nim.storageUtil.videoCoverUrl("https://host/path", 0)

Javavoid getVideoCoverUrl(V2NIMMessageAttachment attachment,
                      V2NIMSize thumbSize,
                      V2NIMSuccessCallback<V2NIMGetMediaResourceInfoResult> success,
                      V2NIMFailureCallback failure);

Objective-C- (void)getVideoCoverUrl:(V2NIMMessageAttachment *)attachment
               thumbSize:(V2NIMSize *)thumbSize
                 success:(V2NIMGetVideoCoverUrlSuccess)success
                 failure:(V2NIMFailureCallback)failure;

C++virtual void v2::V2NIMStorageService::getVideoCoverUrl ("const nstd::shared_ptr< V2NIMMessageAttachment > & attachment,
const nstd::optional< V2NIMSize > & thumbSize,
const V2NIMSuccessCallback< const V2NIMGetMediaResourceInfoResult & > & success,
const V2NIMFailureCallback & failure
)

TypeScriptgetVideoCoverUrl(attachment: V2NIMMessageAttachment, thumbSize: V2NIMSize): Promise<V2NIMGetMediaResourceInfoResult>

Java// 从消息中获取附件，只能使用 V2NIMMessageVideoAttachment
V2NIMMessageAttachment attachment = message.getAttachment();
// 指定图片大小。0 表示该维度不限制
V2NIMSize thumbSize = new V2NIMSize();
thumbSize.setWidth(100);
thumbSize.setHeight(0);

NIMClient.getService(V2NIMStorageService.class).getVideoCoverUrl(attachment, thumbSize, s -> {
    // 获取成功
}, f -> {
    // 获取失败
});

Objective-C// 从消息中获取附件，只能使用 V2NIMMessageVideoAttachment
V2NIMMessageAttachment *attachment = message.attachment;
// 指定图片大小。0 表示该维度不限制
V2NIMSize *thumbSize = [[V2NIMSize alloc] initWithWidth:100 height:0];

[[NIMSDK sharedSDK].v2StorageService getVideoCoverUrl:attachment thumbSize:thumbSize success:^(V2NIMGetMediaResourceInfoResult *result) {
    // 获取成功
} failure:^(V2NIMError *error) {
    // 获取失败
}];

C++storageService.getVideoCoverUrl(attachment, V2NIMSize(150, 150), [](const V2NIMGetMediaResourceInfoResult& result) {
       // get video cover url succeeded
   }, [](V2NIMError error) {
       // get video cover url failed, handle error
   });

TypeScript /**
   * 生成视频封面图链接
   *
   * ESM 模式时，需要动态引入 V2NIMStorageUtil 后使用:
   * NIM.registerService(V2NIMStorageUtil, 'V2NIMStorageUtil')
   *
   * 使用示例: nim.V2NIMStorageService.getVideoCoverUrl(attachment, { width: 100, height: 100 })
   */
  getVideoCoverUrl(attachment: V2NIMMessageAttachment, thumbSize: V2NIMSize): Promise<V2NIMGetMediaResourceInfoResult>

无。

Promise<V2NIMGetMediaResourceInfoResult>

• 请求成功，返回 V2NIMSuccessCallback<V2NIMGetMediaResourceInfoResult> 回调，包含附件下载路径。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储服务相关错误码。

• 请求成功，返回 V2NIMGetVideoCoverUrlSuccess 回调，包含附件下载路径。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储服务相关错误码。

无。

Java/**
 * 下载消息附件
 *
 * @param downloadParam 下载参数
 * @param success       下载消息附件成功回调
 * @param failure       下载消息附件失败回调
 * @param progress      下载消息附件进度回调
 */
void downloadAttachment(V2NIMDownloadMessageAttachmentParams downloadParam,
                        V2NIMSuccessCallback<String> success,
                        V2NIMFailureCallback failure,
                        V2NIMProgressCallback progress);

Objective-C- (void) downloadAttachment:    (V2NIMDownloadMessageAttachmentParams *)     downloadParam
                    success:        (V2NIMDownloadAttachmentSuccess)     success
                    failure:        (V2NIMFailureCallback)     failure
                   progress:        (nullable V2NIMProgressCallback)     progress

C++virtual void v2::V2NIMStorageService::downloadAttachment(const V2NIMDownloadMessageAttachmentParams & downloadParam,
                                                         const V2NIMSuccessCallback< const nstd::string & > & success,
                                                         const V2NIMFailureCallback & failure,
                                                         const V2NIMProgressCallback & progress
)

Java// 从消息中获取附件
// 只有 V2NIMMessageFileAttachment 及其子类可以用于下载原始资源
// 只有 V2NIMMessageImageAttachment 可以用于下载缩略图
// 只有 V2NIMMessageVideoAttachment 可以用于下载视频封面
V2NIMMessageAttachment attachment = message.getAttachment();
// 下载缩略图。
// 下载原始资源使用 V2NIM_DOWNLOAD_ATTACHMENT_TYPE_SOURCE、下载视频封面使用 V2NIM_DOWNLOAD_ATTACHMENT_TYPE_VIDEO_COVER
V2NIMDownloadAttachmentType type = V2NIMDownloadAttachmentType.V2NIM_DOWNLOAD_ATTACHMENT_TYPE_THUMBNAIL;
// 下载缩略图或者视频封面时，指定图片大小。0 表示该维度不限制
V2NIMSize thumbSize = new V2NIMSize();
thumbSize.setWidth(100);
thumbSize.setHeight(0);
// 填写对应消息的端侧 ID，使得下载完成后替换附件中的路径
String messageClientId = message.getMessageClientId();
// 指定文件的存储路径
String saveAs = "path/to/save";

V2NIMDownloadMessageAttachmentParams downloadParam = new V2NIMDownloadMessageAttachmentParams.V2NIMDownloadMessageAttachmentParamsBuilder(attachment)
        .type(type)
        .thumbSize(thumbSize)
        .messageClientId(messageClientId)
        .saveAs(saveAs).build();
NIMClient.getService(V2NIMStorageService.class).downloadAttachment(downloadParam, s -> {
    // 下载成功
}, f -> {
    // 下载失败
}, progress -> {
    // 下载进度变更
});

Objective-C// 从消息中获取附件
// 只有 V2NIMMessageFileAttachment 及其子类可以用于下载原始资源
// 只有 V2NIMMessageImageAttachment 可以用于下载缩略图
// 只有 V2NIMMessageVideoAttachment 可以用于下载视频封面
V2NIMMessageAttachment *attachment = message.attachment;
V2NIMDownloadMessageAttachmentParams *downloadParams = [[V2NIMDownloadMessageAttachmentParams alloc] initWithAttachment:attachment];
// 下载缩略图。
// 下载原始资源使用 V2NIM_DOWNLOAD_ATTACHMENT_TYPE_SOURCE、下载视频封面使用 V2NIM_DOWNLOAD_ATTACHMENT_TYPE_VIDEO_COVER
downloadParams.type = V2NIM_DOWNLOAD_ATTACHMENT_TYPE_THUMBNAIL;
// 下载缩略图或者视频封面时，指定图片大小。0 表示该维度不限制
downloadParams.thumbSize = [[V2NIMSize alloc] initWithWidth:100 height:0];
// 填写对应消息的端侧 ID，使得下载完成后替换附件中的路径
downloadParams.messageClientId = message.messageClientId;
// 指定文件的存储路径
downloadParams.saveAs = @"path/to/save";

[[NIMSDK sharedSDK].v2StorageService downloadAttachment:attachment success:^(NSString *filePath) {
    // 下载成功
} failure:^(V2NIMError *error) {
    // 下载失败
} progress:^(NSUInteger progress) {
    // 下载进度变更
}];

C++V2NIMDownloadMessageAttachmentParams downloadParam;
downloadParam.attachment = attachment;
downloadParam.type = V2NIM_DOWNLOAD_ATTACHMENT_TYPE_SOURCE;
storageService.downloadAttachment(
    downloadParam,
    [](const nstd::string& path) {
        // download attachment succeeded
    },
    [](V2NIMError error) {
        // download attachment failed, handle error
    },
    [](uint32_t progress) {
        // download progress
    });

• 请求成功，返回 V2NIMSuccessCallback 回调，包含附件下载路径。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储服务相关错误码。
• 返回 V2NIMProgressCallback 回调，包含附件下载进度。

• 请求成功，返回 V2NIMDownloadAttachmentSuccess 回调，包含附件下载路径。
• 请求失败，返回 V2NIMFailureCallback 回调，包含存储服务相关错误码。
• 返回 V2NIMProgressCallback 回调，包含附件下载进度。