Alamofire: [Result]: FAILURE: Error Domain=NSURLErrorDomain Code=-999 “cancelled”

The service I'm connecting to is using a self signed certificate. For dev purposes I do not want to validate that chain.

Using swift 3 with Alamofire 4. Fixed the ATS accordingly:

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSExceptionDomains</key>
    <dict>
        <key>url.com</key>
        <dict>
            <key>NSExceptionAllowsInsecureHTTPLoads</key>
            <true/>
            <key>NSExceptionRequiresForwardSecrecy</key>
            <false/>
            <key>NSIncludesSubdomains</key>
            <true/>
        </dict>
    </dict>
</dict>

Code to connect and disable evaluation.

    let serverTrustPolicies: [String: ServerTrustPolicy] = [
        "example.domain.com": .pinCertificates(
            certificates: ServerTrustPolicy.certificates(),
            validateCertificateChain: false,
            validateHost: true
        ),
        "sub.url.com": .disableEvaluation
    ]

    let sessionManager = Alamofire.SessionManager(
        serverTrustPolicyManager: ServerTrustPolicyManager(policies: serverTrustPolicies)
    )

    let headers = ["Authorization": "Basic /*...*/"]

    sessionManager.request("https://sub.url.com/path", headers: headers).responseJSON { response in
        print(response.request)  // original URL request
        print(response.response) // HTTP URL response
        print(response.data)     // server data
        print(response.result)   // result of response serialization

        debugPrint(response)

        if let JSON = response.result.value {
            print("JSON: \(JSON)")
        }
    }

Error log from dumpPrint

[Result]: FAILURE: Error Domain=NSURLErrorDomain Code=-999 "cancelled" UserInfo={NSErrorFailingURLKey=https://sub.url.com/path, NSLocalizedDescription=cancelled, NSErrorFailingURLStringKey=https://sub.url.com/path}

URL has been masked.

To retain SessionManager instance you need to capture it in closure passed to responseJSON:

sessionManager.request("https://sub.url.com/path", headers: headers).responseJSON { response in
    let _ = sessionManager // retain
    // ...
}

Otherwise sessionManager is deallocated shortly it goes out of scope and any executing requests are cancelled.

Please add this statement to the end of responseJson block:

manager.session.invalidateAndCancel()

It happens if the object of the manager is not retained till execution of the block completes, so this would ensure its retention.

Cheers!

john7ric

Please check in sessiondidReceiveChallenge: delegate implementation of NSURLSession. Chances are NSURLSessionAuthChallengeCancelAuthenticationChallenge is getting executed somewhere.

self.getSessionManager().request(urlstring, method: methods, parameters: parameters, encoding: JSONEncoding.prettyPrinted, headers: Header).responseJSON(queue: nil, options: JSONSerialization.ReadingOptions.allowFragments) { (responseObject) in ... .... }.session.finishTasksAndInvalidate()

Just put the method of invalidate after task finish, means session.finishTasksAndInvalidate()

You need to properly manage the lifetime of your SessionManager instance. Most commonly this is done by making a singleton instance. Otherwise, when your manager goes out of scope and is deinited, all outstanding requests will be cancelled.

来源：https://stackoverflow.com/questions/39984880/alamofire-result-failure-error-domain-nsurlerrordomain-code-999-cancelled

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