QCloudCOSSMHDownloadObjectRequest *req = [QCloudCOSSMHDownloadObjectRequest new];

// full file path
req.filePath = @"filepath";
// Media Library ID, required parameter
req.libraryId = @"libraryId";
// Space ID. If the media library is in single-tenant mode, this parameter is fixed as a hyphen (-); if the media library is in multi-tenant mode, you must specify this parameter.
req.spaceId = @"spaceId";
// When this option is set to YES, it will compare the crc64 of the file stored in COS with the crc64 of the file downloaded to local after download completion
Currently enabled by default.
req.enableCRC64Verification = YES;
// Whether to use part and resume download, defaults to YES.
req.resumableDownload = YES;
// Local download path
req.downloadingURL = cto.tempFileURL;
// Progress callback
[req setDownProcessBlock:^(int64_t bytesDownload, int64_t totalBytesDownload, int64_t totalBytesExpectedToDownload) {

}];
// Complete callback
[req setFinishBlock:^(id outputObject, NSError *error) {

}];
[[QCloudSMHService defaultSMHService] smhDownload:req];

[request cancel];

[request remove];