Swift-JSON响应以u201c开头，以u201d结尾

我有一个Swift脚本，它现在的目的是首先向PHP文件发送一个JSON字符串；第二，返回发送到XCODE控制台中解析的php脚本的值；第三个返回下面的值之一。但是，我的字符串返回的值以''u201C开头，以''u201d结尾。

有人能告诉我吗？首先，为什么要这样做，其次，如何解决？

override func viewDidLoad() {
        super.viewDidLoad()

        let myUrl = NSURL(string: "http://localhost/phpPost/demo.php");
        let request = NSMutableURLRequest(URL: myUrl!);
        request.HTTPMethod = "POST";

let postString = "firstName=James&lastName=Bond";
request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding);
let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
    data, response, error in
    if error != nil {
        println("error='(error)")
        return
    }
    println("******response = '(response)")
    // Print out response body
    let responseString = NSString(data: data, encoding: NSUTF8StringEncoding)
    println("****response data='(responseString)")
    //Let’s convert response sent from a server side script to a NSDictionary object:
    var err: NSError?
    var myJSON = NSJSONSerialization.JSONObjectWithData(data, options: .MutableLeaves, error:&err) as? NSDictionary
    if let parseJSON = myJSON {
        var firstNameValue = parseJSON["firstName"] as? String
        println("firstName: '(firstNameValue)")
    }
}
task.resume()

此外，这里还有PHP:

<?php
$firstName= $_REQUEST["firstName"];
$lastName = $_REQUEST["lastName"];// Store values in an array
$returnValue = array(“firstName”=>$firstName, “lastName”=>$lastName);
// Send back request in JSON format
echo json_encode($returnValue); 
?>

以下是返回的内容：

****response data=可选（｛"''u201cfirstName''u201d"："James"，"''u201classtName''u201"："Bond"｝）firstName:nil