ios FTP upload using NSURLSession

Question

I am trying to upload files via FTP to server. According to Apple Documentation NSURLSession class supports FTP operations.

There is a famous Apple Developer blog which also supports that. But still its not clear whether NSURLSession API's supports ftp upload or not? (I tried with the way suggested and getting error).

With the conventional way of CFFTPStreamRef, ftp upload works fine but it's deprecated in 9.0. The header says: CF_DEPRECATED(10_3, 10_11, 2_0, 9_0 , "Use NSURLSessionAPI for ftp requests")

Any idea, example or link to get help with. I am trying something like this for now:

NSURL *url_upload = [NSURL URLWithString:@"ftp://username:password@thelink/myfolder/filename.zip"];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url_upload];
    [request setHTTPMethod:@"PUT"];
NSURL *docsDirURL = [NSURL fileURLWithPath:filePath];

NSURLProtectionSpace * protectionSpace = [[NSURLProtectionSpace alloc] initWithHost:url_upload.host port:[url_upload.port integerValue] protocol:url_upload.scheme realm:nil authenticationMethod:nil];

NSURLCredential *cred = [NSURLCredential
                         credentialWithUser:userId
                         password:password
                         persistence:NSURLCredentialPersistenceForSession];


NSURLCredentialStorage * cred_storage ;
[cred_storage setCredential:cred forProtectionSpace:protectionSpace];
NSURLSessionConfiguration *sessionConfig = [NSURLSessionConfiguration defaultSessionConfiguration];
sessionConfig.URLCredentialStorage = cred_storage;
sessionConfig.timeoutIntervalForRequest = 30.0;
sessionConfig.timeoutIntervalForResource = 60.0;
sessionConfig.allowsCellularAccess = YES;
sessionConfig.HTTPMaximumConnectionsPerHost = 1;
NSURLSession *upLoadSession = [NSURLSession sessionWithConfiguration:sessionConfig delegate:self delegateQueue:nil];
NSURLSessionUploadTask *uploadTask = [upLoadSession uploadTaskWithRequest:request fromFile:docsDirURL];
[uploadTask resume];

Answer 1

To the best of my recollection, NSURLSession (and NSURLConnection) support retrieving files via FTP, but do not support any other FTP commands, such as STOR (note that PUT is an HTTP method, not an FTP method).

For your purposes, your options are to either use the CFFTPStream API (which only barely works) or stop using FTP.

My strong recommendation would be to stop using FTP. The FTP protocol is hopelessly insecure, sending the username and password in cleartext form over the wire, which makes it really easy for people to sniff the credentials and masquerade as the user. So the only situation where an FTP upload would be even remotely acceptable these days is an anonymous FTP upload to a shared dropbox, and even then, it is somewhat dubious. That's why the functionality was never added to the NSURLConnection API, much less NSURLSession.

There are much better alternatives that are much more secure, such as WebDAV over HTTPS, POST request uploads over HTTPS, WebDAV or POST requests with digest authentication, etc. And those alternatives are actually supportable with NSURLSession and provide other advantages like the ability to resume downloads. Unless you have absolutely no way to change the server side, please use one of those alternatives instead.