我目前正在iOS应用中使用Black Raccoon库，使用以下建议代码将小文件上传到FTP服务器：
- (IBAction) uploadFile :(id)sender {
//----- get the file path for the item we want to upload
NSString *applicationDocumentsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *filepath = [NSString stringWithFormat: @"%@/%@", applicationDocumentsDir, @"file.text"];
//----- read the entire file into memory (small files only)
uploadData = [NSData dataWithContentsOfFile: filepath];
//----- create our upload object
uploadFile = [[BRRequestUpload alloc] initWithDelegate: self];
//----- for anonymous login just leave the username and password nil
uploadFile.path = @"/home/user/myfile.txt";
uploadFile.hostname = @"192.168.1.100";
uploadFile.username = @"yourusername";
uploadFile.password = @"yourpassword";
//----- we start the request
[uploadFile start]; }
- (NSData *) requestDataToSend: (BRRequestUpload *) request {
//----- returns data object or nil when complete
//----- basically, first time we return the pointer to the NSData.
//----- and BR will upload the data.
//----- Second time we return nil which means no more data to send
NSData *temp = uploadData; // this is a shallow copy of the pointer
uploadData = nil; // next time around, return nil...
return temp; }
上传大文件（大于50MB）需要做什么，而无需将整个文件写入内存？