Using NSURLSession with SSL public key pinning

gistfile1.m

/*
  1. Adhere to the NSURLSessionDelegate delegate
  2. Initialize NSURLSession and specify self as delegate (e.g. [NSURLSession sessionWithConfiguration:defaultConfigObject delegate:self delegateQueue: [NSOperationQueue mainQueue]];)
  3. Add the method below to your class
  4. Change the certificate resource name
*/
 
- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential *))completionHandler
{
    SecTrustRef serverTrust = challenge.protectionSpace.serverTrust;
    SecCertificateRef certificate = SecTrustGetCertificateAtIndex(serverTrust, 0);
    NSData *remoteCertificateData = CFBridgingRelease(SecCertificateCopyData(certificate));
    NSString *cerPath = [[NSBundle mainBundle] pathForResource:@"myCertName" ofType:@"cer"];
    NSData *localCertData = [NSData dataWithContentsOfFile:cerPath];
    
    if ([remoteCertificateData isEqualToData:localCertData])
    {
        NSURLCredential *credential = [NSURLCredential credentialForTrust:serverTrust];
        [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
        completionHandler(NSURLSessionAuthChallengeUseCredential, credential);
    }
    else
    {
        [[challenge sender] cancelAuthenticationChallenge:challenge];
        completionHandler(NSURLSessionAuthChallengeRejectProtectionSpace, nil);
    }
}