nsurlconnection.m

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
    // gets a certificate from local resources
    NSString *thePath = [[NSBundle mainBundle] pathForResource:@"MyCertificate" ofType:@"pfx"];
    NSData *PKCS12Data = [[NSData alloc] initWithContentsOfFile:thePath];
    CFDataRef inPKCS12Data = (CFDataRef)PKCS12Data;
    SecIdentityRef identity;

    // extract the ideneity from the certificate
    [self extractIdentity :inPKCS12Data :&identity];

    SecCertificateRef certificate = NULL;
    SecIdentityCopyCertificate (identity, &certificate);

    const void *certs[] = {certificate};
    CFArrayRef certArray = CFArrayCreate(kCFAllocatorDefault, certs, 1, NULL);

    // create a credential from the certificate and ideneity, then reply to the challenge with the credential
    NSURLCredential *credential = [NSURLCredential credentialWithIdentity:identity certificates:(NSArray*)certArray persistence:NSURLCredentialPersistencePermanent];
    [challenge.sender useCredential:credential forAuthenticationChallenge:challenge];
}