CODE EXAMPLE FOR SWIFT

swift api call certificate

public class MyURLSessionDelegate: NSObject, URLSessionDelegate {
    public func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
        // `NSURLAuthenticationMethodClientCertificate`
        // indicates the server requested a client certificate.
        if challenge.protectionSpace.authenticationMethod
             != NSURLAuthenticationMethodClientCertificate {
                completionHandler(.performDefaultHandling, nil)
                return
        }

        guard let file = Bundle(for: HTTPAccessURLSessionDelegate.self).url(forResource: p12Filename, withExtension: "p12"),
              let p12Data = try? Data(contentsOf: file) else {
            // Loading of the p12 file's data failed.
            completionHandler(.performDefaultHandling, nil)
            return
        }

        // Interpret the data in the P12 data blob with
        // a little helper class called `PKCS12`.
        let password = "MyP12Password" // Obviously this should be stored or entered more securely.
        let p12Contents = PKCS12(pkcs12Data: p12Data, password: password)
        guard let identity = p12Contents.identity else {
            // Creating a PKCS12 never fails, but interpretting th contained data can. So again, no identity? We fall back to default.
            completionHandler(.performDefaultHandling, nil)
            return
        }

        // In my case, and as Apple recommends,
        // we do not pass the certificate chain into
        // the URLCredential used to respond to the challenge.
        let credential = URLCredential(identity: identity,
                                   certificates: nil,
                                    persistence: .none)
        challenge.sender?.use(credential, for: challenge)
        completionHandler(.useCredential, credential)
    }
}