how to partial download a file from google drive use objective c? - objective-c

Question

I wanna download a big file from google drive use objective,and I use the google-api-objectivec-client-read-only lib.But when I download the big file,I see the memory boom up.
For example,the file's size is 589M,the program's memory more than 600M.So I wannna partial download the file from google drive.
My code:
-(void)getFileMetadataWithService:(NSString *)fileId
{
GTLQuery *query = [GTLQueryDrive queryForFilesGetWithFileId:fileId];
[service executeQuery:query
completionHandler:^(GTLServiceTicket *ticket, GTLDriveFile *file,
NSError *error) {
if (error == nil) {
NSLog(#"Title: %#", file.title);
NSLog(#"Description: %#", file.descriptionProperty);
NSLog(#"MIME type: %#", file.mimeType);
NSLog(#"download url:%#",file.downloadUrl);
NSLog(#"export link:%#",file.exportLinks);
[self downloadFileContentWithService:#"example"
file:file];
} else {
NSLog(#"An error occurred: %#", error);
}
}];
}
-(void)downloadFileContentWithService:(NSString *)loaclpath
file:(GTLDriveFile *)file
{
NSLog(#"download file");
if (file.downloadUrl != nil)
{
NSLog(#"begin download");
GTMHTTPFetcher *fetcher =[service.fetcherService fetcherWithURLString:file.downloadUrl];
[fetcher beginFetchWithCompletionHandler:^(NSData *data, NSError *error) {
if (error == nil) {
[data writeToFile:#"/Users/mycomputer/Desktop/a.mov" atomically:YES];
[data writeToFile:#"/Users/mycomputer/Desktop/b.mov" atomically:YES];
[data writeToFile:#"/Users/mycomputer/Desktop/c.mov" atomically:YES];
NSLog(#"download ok");
} else {
NSLog(#"An error occurred: %#", error);
}
}];
}
else
{
}
}
How to modify the method to partial download a file from google drive?

Answer 1

OK,I fix it up.It is so easy.
I modify the code as:
-(void)downloadFileContentWithService:(NSString *)loaclpath
file:(GTLDriveFile *)file
{
NSLog(#"download file");
if (file.downloadUrl != nil)
{
NSLog(#"begin download");
GTMHTTPFetcher *fetcher =[service.fetcherService fetcherWithURLString:file.downloadUrl];
fetcher.downloadPath = #"/Users/KarlDoenitz/Desktop/download/bisaishipin.mov";
[fetcher beginFetchWithCompletionHandler:^(NSData *data, NSError *error) {
if (error == nil) {
NSLog(#"download ok");
} else {
NSLog(#"An error occurred: %#", error);
}
}];
}
else
{
}
}