Alamofire .POST response JSON nil using PHP-open source projects Alamofire/Alamofire

How can I get JSON values back from my PHP script?

I get nil in my JSON response.

The Alamofire.request works. (i.e. I receive JSON data at my PHP script.)

The PHP script works. (i.e. I can process the input JSON and I generate a valid JSON string using json_encode.)

Here’s the code…

Swift:

Alamofire
    .request(.POST, "http://www.myserver.com/from_swift.php", parameters: dicMyDictionary, encoding: ParameterEncoding.JSON)
    .responseJSON {
        (request, response, JSON, error) in
        println("request: \(request)")
        println("response: \(response)")
        println("JSON: \(JSON)")
        println("error: \(error)")
}

Println Results:

request:  { URL: http://www.myserver/from_swift.php }

response: Optional( { URL: http://www.myserver/from_swift.php } { status code: 200, headers {
    Connection = "Keep-Alive";
    "Content-Type" = "application/json";
    Date = "Fri, 16 Jan 2015 12:02:24 GMT";
    "Keep-Alive" = "timeout=5, max=200";
    Server = "Apache/2.2.29 (Unix)";
    "Transfer-Encoding" = Identity;
    "X-Powered-By" = "PHP/5.4.36";
} })

JSON: nil

error: Optional(Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (Invalid value around character 0.) UserInfo=0x7ff3b380db80 {NSDebugDescription=Invalid value around character 0.})

PHP:

Solution: I had an error in my PHP script. As a result, the error message was being passed back in the response before the JSON string. As a result, the .responseJSON correctly didn’t recognize the data as JSON.

To help others, when you’re getting nil in your data parameter from .responseJSON, troubleshoot by changing .responseJSON to .responseString to see if you get any results back in the data parameter. For example, when I changed to .responseString I saw the following:

JSON: Optional("
\nStrict Standards:  mysqli::next_result(): There is no next result set. Please, call mysqli_more_results()/mysqli::more_results() to check whether to call this function/method in /home/xxx/public_html/from_swift.php on line 115
\n{\"books\":[\"the hunger games\",\"mockingjay\"]}")

Notice, the error message in front of the json string. After I corrected the PHP script and changed back to .responseJSON, it worked…