NSURL *url = [NSURL URLWithString:@"http://sharepoint.example.com/"];
NSURLCredential *credential = [credentialWithUser:@"username"
                                         password:@"password"
                                      persistence:NSURLCredentialPersistenceNone];
self.ctx = [[SPContext alloc] initWithSiteURL:url];
[self.ctx setRequestSetupBlock:^(SPURLConnectionOperation *requestOperation) {
    // Called when a new request is allocated
    [requestOperation setAuthenticationChallengeBlock:^(NSURLConnection *connection, NSURLAuthenticationChallenge *challenge) {
        [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
    }];
}];

[self.ctx getListCollection:^(NSArray *lists, NSError *error) {
    for (SPList *list in lists) {
        NSLog(@"%@", list.title);
    }
}];