rrr.swift:356:72: Ambiguous use of 'subscript'

self.restApi.getSchoolDetails(schoolId) {responseObject, error in
        // use responseObject and error here

         self.schoolDetailsCollection = NSDictionary(dictionary: responseObject! as! [String : AnyObject])
         print(self.schoolDetailsCollection)

        if let response = responseObject as? NSDictionary {
           //parse the response object
            self.schoolDetailsList = (response as? NSDictionary)!

            //assigning all values to shareData class
            self.shareData.sco_id = response["result"]!["sco_id"] as!NSInteger
            self.shareData.address = response["result"]!["address"] as!String
            self.shareData.name = response["result"]!["name"] as! String
            print("school name")
            print(self.shareData.name)
            self.shareData.intro = response["result"]!["intro"] as! String
           self.shareData.sell_point = response["result"]!["sell_point"] as! String
            self.shareData.city = response["result"]!["city"] as! String
            self.shareData.cou_id = response["result"]!["cou_id"] as! String

            //get images from the nested array in the json array
            /THESE THREE LINES CAUSE THE ERROR SUBSRCIPT
             self.shareData.image1 = response["result"]!["images"][0]! as! String
            self.shareData.image2 = response["result"]!["images"]![1] as! String
            self.shareData.image3 = response["result"]!["images"]![2] as! String

            print(self.shareData.image1)
            print(self.shareData.image2)
            print(self.shareData.image3)



            //open next controller after all info has been set correctly
            //info is being passed by Singleton class Sharedata
            if let COBezierDemoViewController = self.storyboard!.instantiateViewControllerWithIdentifier("COBezierDemoViewController") as? COBezierDemoViewController {
                self.presentViewController(COBezierDemoViewController, animated: true, completion: nil)
            }

        }

    }

}

{
result =     {
    address = "223 Vincent St, West Perth WA 6005, Australia";
    city = Perth;
    "cou_id" = AU;
    "cur_id" = "";
    environment = R;
    financed = "<null>";
    images =         (
        "Phoenix_Academy_1.jpeg",
        "Phoenix_Academy_3.jpeg",
        "Phoenix_Academy_2.jpeg"
    );
    intro = "Our language school in Perth has a modern campus and a spacious garden. The language school is located 10 minutes north from the city center. You can reach the city center and the famous bea