在iOS 9中，对于所有无效或自签名的证书，SSL连接将失败。这是iOS 9.0或更高版本、OS X 10.11及更高版本中新的应用程序传输安全特性的默认行为。

您可以在“信息”中覆盖此行为。通过在NSAppTransportSecurity字典中将NSAllowsArbitraryLoads设置为YES。但是，我建议仅为测试目的重写此设置。

有关信息，请参阅这里的应用程序传输技术说明。

与AFNetworking我已经成功地消费https webservice与以下代码，

NSString *aStrServerUrl = WS_URL;

// Initialize AFHTTPRequestOperationManager...
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
manager.requestSerializer = [AFJSONRequestSerializer serializer];
manager.responseSerializer = [AFJSONResponseSerializer serializer];

[manager.requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
manager.securityPolicy.allowInvalidCertificates = YES; 
[manager POST:aStrServerUrl parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject)
{
    successBlock(operation, responseObject);

} failure:^(AFHTTPRequestOperation *operation, NSError *error)
{
    errorBlock(operation, error);
}];

由Nathan de Vries发布的category工作区将通过AppStore私有API检查，并且在你无法控制NSUrlConnection对象的情况下很有用。 一个例子是NSXMLParser，它将打开你提供的URL，但不公开NSURLRequest或NSURLConnection。

在iOS 4中，解决方法似乎仍然有效，但仅在设备上，模拟器不再调用allowsAnyHTTPSCertificateForHost:方法。

我发布了一些要点代码(基于别人的工作，我注意到)，可以让你正确地验证自己生成的证书(以及如何获得免费证书-见Cocoanetics底部的评论)

我的代码在这里github

To complement the accepted answer, for much better security, you could add your server certificate or your own root CA certificate to keychain( https://stackoverflow.com/a/9941559/1432048), however doing this alone won't make NSURLConnection authenticate your self-signed server automatically. You still need to add the below code to your NSURLConnection delegate, it's copied from Apple sample code AdvancedURLConnections, and you need to add two files(Credentials.h, Credentials.m) from apple sample code to your projects.

- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace {
return [protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust];
}

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
if ([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
//        if ([trustedHosts containsObject:challenge.protectionSpace.host])

    OSStatus                err;
    NSURLProtectionSpace *  protectionSpace;
    SecTrustRef             trust;
    SecTrustResultType      trustResult;
    BOOL                    trusted;

    protectionSpace = [challenge protectionSpace];
    assert(protectionSpace != nil);

    trust = [protectionSpace serverTrust];
    assert(trust != NULL);
    err = SecTrustEvaluate(trust, &trustResult);
    trusted = (err == noErr) && ((trustResult == kSecTrustResultProceed) || (trustResult == kSecTrustResultUnspecified));

    // If that fails, apply our certificates as anchors and see if that helps.
    //
    // It's perfectly acceptable to apply all of our certificates to the SecTrust
    // object, and let the SecTrust object sort out the mess.  Of course, this assumes
    // that the user trusts all certificates equally in all situations, which is implicit
    // in our user interface; you could provide a more sophisticated user interface
    // to allow the user to trust certain certificates for certain sites and so on).

    if ( ! trusted ) {
        err = SecTrustSetAnchorCertificates(trust, (CFArrayRef) [Credentials sharedCredentials].certificates);
        if (err == noErr) {
            err = SecTrustEvaluate(trust, &trustResult);
        }
        trusted = (err == noErr) && ((trustResult == kSecTrustResultProceed) || (trustResult == kSecTrustResultUnspecified));
    }
    if(trusted)
        [challenge.sender useCredential:[NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust] forAuthenticationChallenge:challenge];
}

[challenge.sender continueWithoutCredentialForAuthenticationChallenge:challenge];
}

NSURLRequest有一个叫做setAllowsAnyHTTPSCertificate:forHost:的私有方法，它会做你想做的事情。你可以通过一个类别在NSURLRequest上定义allowsAnyHTTPSCertificateForHost:方法，并设置它为你想要覆盖的主机返回YES。