您已在设备钥匙串上安装了客户端SSL证书.

Safari.app和Mail.app可以访问这个钥匙串,而iOS应用没有.

原因是我们开发的应用程序是沙盒,在非越狱设备中没有任何访问权限.

随着safari访问它,连接和认证服务器的挑战没有任何麻烦.

解：

将导出的P12文件与App捆绑在一起,并引用它来查找服务器正在查找的正确的客户端证书.它实际上是一种解决方法.硬编码是获取P12文件的可靠方法.

执行：

在NSURLConenction委托中的方法是willSendRequestForAuthenticationChallenge.您需要考虑NSURLAuthenticationMethodClientCertificate挑战类型,以处理服务器挑战.这是我们实现了从嵌入式P12文件中提取正确的证书身份的魔力的地方.代码如下

- (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
  if ([challenge prevIoUsFailureCount] > 0) {
       //this will cause an authentication failure
    [[challenge sender] cancelAuthenticationChallenge:challenge];
   NSLog(@"Bad Username Or Password");    
       return;
  }



     //this is checking the server certificate
      if ([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
        SecTrustResultType result;
        //This takes the serverTrust object and checkes it against your keychain
        SecTrustEvaluate(challenge.protectionSpace.serverTrust,&result);

            //if we want to ignore invalid server for certificates,we just accept the server
        if (kSPAllowInvalidServerCertificates) {
          [challenge.sender useCredential:[NSURLCredential credentialForTrust: challenge.protectionSpace.serverTrust] forAuthenticationChallenge: challenge];
                return;
        } else if(result == kSecTrustResultProceed || result == kSecTrustResultConfirm || result == kSecTrustResultUnspecified) {
                //When testing this against a trusted server I got kSecTrustResultUnspecified every time. But the other two match the description of a trusted server
          [challenge.sender useCredential:[NSURLCredential credentialForTrust: challenge.protectionSpace.serverTrust] forAuthenticationChallenge: challenge];
                return;
        }
      } else if ([[challenge protectionSpace] authenticationMethod] == NSURLAuthenticationMethodClientCertificate) {
       //this handles authenticating the client certificate

       /* 
 What we need to do here is get the certificate and an an identity so we can do this:
   NSURLCredential *credential = [NSURLCredential credentialWithIdentity:identity certificates:myCerts persistence:NSURLCredentialPersistencePermanent];
   [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];

   It's easy to load the certificate using the code in -installCertificate
   It's more difficult to get the identity.
   We can get it from a .p12 file,but you need a passphrase:
   */

   NSString *p12Path = [[BundleManager bundleForCurrentSkin] pathForResource:kP12FileName ofType:@"p12"];
   NSData *p12Data = [[NSData alloc] initWithContentsOfFile:p12Path];

   CFStringRef password = CFSTR("PASSWORD");
   const void *keys[] = { kSecImportExportPassphrase };
   const void *values[] = { password };
   CFDictionaryRef optionsDictionary = CFDictionaryCreate(NULL,keys,values,1,NULL,NULL);
   CFArrayRef p12Items;

   OSStatus result = SecPKCS12Import((CFDataRef)p12Data,optionsDictionary,&p12Items);

   if(result == noErr) {
      CFDictionaryRef identityDict = CFArrayGetValueAtIndex(p12Items,0);
      SecIdentityRef identityApp =(SecIdentityRef)CFDictionaryGetValue(identityDict,kSecImportItemIdentity);

      SecCertificateRef certRef;
      SecIdentityCopyCertificate(identityApp,&certRef);

      SecCertificateRef certArray[1] = { certRef };
      CFArrayRef myCerts = CFArrayCreate(NULL,(void *)certArray,NULL);
      CFRelease(certRef);

      NSURLCredential *credential = [NSURLCredential credentialWithIdentity:identityApp certificates:(NSArray *)myCerts persistence:NSURLCredentialPersistencePermanent];
      CFRelease(myCerts);

      [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
    }
  } else if ([[challenge protectionSpace] authenticationMethod] == NSURLAuthenticationMethodDefault || [[challenge protectionSpace] authenticationMethod] == NSURLAuthenticationMethodNTLM) {
   // For normal authentication based on username and password. This could be NTLM or Default.

        DAVCredentials *cred = _parentSession.credentials;
    NSURLCredential *credential = [NSURLCredential credentialWithUser:cred.username password:cred.password persistence:NSURLCredentialPersistenceForSession];
  [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
  } else {
        //If everything fails,we cancel the challenge.
        [[challenge sender] cancelAuthenticationChallenge:challenge];
    }
}

参考：
Ref1,Ref2,Ref3

希望这可以帮助