AuthenticationChallenge is called just once - ios

Question

I'm using NSURLConnection to connect to a server. It uses basic authorization. This is my code:
- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
if ([challenge previousFailureCount] == 0) {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSURLCredential *newCredential = [NSURLCredential credentialWithUser:[defaults objectForKey:#"SavedUserName"]
password:[defaults objectForKey:#"SavedPassword"]
persistence:NSURLCredentialPersistenceForSession];
[[challenge sender] useCredential:newCredential forAuthenticationChallenge:challenge];
}
else {
[self doAlert:#"Cannot acces server" omg:#"Check your login properties"];
}
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
NSLog(#"11111111111");
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
NSLog(#"222222222");
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSLog(#"333333333333");
}
- (void)checkIfCanLogin{
[conn cancel];
conn = nil;
//setting request and so on
conn = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[conn start];
}
For first tries is everything ok. - I enter wrong pw, Alert is called. When I enter right password connection is loaded. But when I establish connection, I change password and after that call checkIfCanLogin again, -(void)didRecieveAuth... is not called. That means function returns that server is accessible, but it actually is not.
Any ideas how to improve my code? thanks a lot.

Answer 1

If you look at CredentialsController.m in Apple's AdvancedURLConnections, they illustrate how to purge credentials.
NSURLCredentialStorage *store = [NSURLCredentialStorage sharedCredentialStorage];
assert(store != nil);
for (NSURLProtectionSpace * protectionSpace in [store allCredentials]) {
NSDictionary *userToCredentialMap = [[NSURLCredentialStorage sharedCredentialStorage] credentialsForProtectionSpace:protectionSpace];
assert(userToCredentialMap != nil);
for (NSString * user in userToCredentialMap) {
NSURLCredential *credential = [userToCredentialMap objectForKey:user];
assert(credential != nil);
[store removeCredential:credential forProtectionSpace:protectionSpace];
}
}
The Credentials.m code sample also shows how to purge credentials from the key chain.