Swift 3+ 更新：

只需定义一个委托类NSURLSessionDelegate并实现didReceiveChallenge函数（ 此代码改编自Objective-c
OWASP示例 ）：

class NSURLSessionPinningDelegate: NSObject, URLSessionDelegate {

    func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Swift.Void) {

        // Adapted from OWASP https://www.owasp.org/index.php/Certificate_and_Public_Key_Pinning#iOS

        if (challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust) {
            if let serverTrust = challenge.protectionSpace.serverTrust {
                let isServerTrusted = SecTrustEvaluateWithError(serverTrust, nil)

                if(isServerTrusted) {
                    if let serverCertificate = SecTrustGetCertificateAtIndex(serverTrust, 0) {
                        let serverCertificateData = SecCertificateCopyData(serverCertificate)
                        let data = CFDataGetBytePtr(serverCertificateData);
                        let size = CFDataGetLength(serverCertificateData);
                        let cert1 = NSData(bytes: data, length: size)
                        let file_der = Bundle.main.path(forResource: "certificateFile", ofType: "der")

                        if let file = file_der {
                            if let cert2 = NSData(contentsOfFile: file) {
                                if cert1.isEqual(to: cert2 as Data) {
                                    completionHandler(URLSession.AuthChallengeDisposition.useCredential, URLCredential(trust:serverTrust))
                                    return
                                }
                            }
                        }
                    }
                }
            }
        }

        // Pinning failed
        completionHandler(URLSession.AuthChallengeDisposition.cancelAuthenticationChallenge, nil)
    }

}

（您可以在此处找到Swift
2的Gist-
从初始答案开始）

然后使用创建.der网站的文件openssl

openssl s_client -connect my-https-website.com:443 -showcerts < /dev/null | openssl x509 -outform DER > my-https-website.der

并将其添加到xcode项目。仔细检查列表中的Build phases标签中是否存在该标签Copy Bundle Resources。否则，将其拖放到此列表中。

最后在代码中使用它来发出URL请求：

if let url = NSURL(string: "https://my-https-website.com") {

    let session = URLSession(
            configuration: URLSessionConfiguration.ephemeral,
            delegate: NSURLSessionPinningDelegate(),
            delegateQueue: nil)


    let task = session.dataTask(with: url as URL, completionHandler: { (data, response, error) -> Void in
        if error != nil {
            print("error: \(error!.localizedDescription): \(error!)")
        } else if data != nil {
            if let str = NSString(data: data!, encoding: String.Encoding.utf8.rawValue) {
                print("Received data:\n\(str)")
            } else {
                print("Unable to convert data to text")
            }
        }
    })

    task.resume()
} else {
    print("Unable to create NSURL")
}