macOS Swift Question: Label Text

import Cocoa


@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

    @IBOutlet weak var window: NSWindow!
    @IBOutlet weak var lblLeadsCount: NSTextField!
    @IBOutlet weak var lblLastChecked: NSTextField!


    func applicationDidFinishLaunching(aNotification: NSNotification?) {
        // Insert code here to initialize your application
    }

    func applicationWillTerminate(aNotification: NSNotification?) {
        // Insert code here to tear down your application
    }

    @IBAction func checkLeads(sender: AnyObject) {
        var url = NSURL(string: "http://*********************")
        let theRequest = NSURLRequest(URL: url!)
        
        NSURLConnection.sendAsynchronousRequest(theRequest, queue: nil, completionHandler: {(response: NSURLResponse!, data: NSData!, error: NSError!) -> Void in
            if data.length > 0 && error == nil {
                let response : AnyObject! = NSJSONSerialization.JSONObjectWithData(data,
                    options: NSJSONReadingOptions.MutableContainers, error: nil)
                
                lblLeadsCount.text = response
            }
        })
    }

}

lblLeadsCount.text = response

self.lblLeadsCount.stringValue = "test";