SecCertificateRef certificate =  SecCertificateCreateWithData(NULL, (CFDataRef) certificateData);

CFArrayRef rootCerts = (CFArrayRef)[client.additionalRootCertificates allObjects];
        SecTrustResultType result;
        OSStatus returnCode;

        if (rootCerts && CFArrayGetCount(rootCerts)) {
            // this could fail, but the trust evaluation will proceed (it's likely to fail, of course)
            SecTrustSetAnchorCertificates(trust, rootCerts);
        }

        returnCode = SecTrustEvaluate(trust, &result);

        if (returnCode == errSecSuccess) {
            proceed = (result == kSecTrustResultProceed || result == kSecTrustResultConfirm || result == kSecTrustResultUnspecified);
            if (result == kSecTrustResultRecoverableTrustFailure) {
                // TODO: should try to recover here
                // call SecTrustGetCssmResult() for more information about the failure
            }
        }