swift | unresolved identifier error - swift3

Question

Here is the code:
let task: URLSessionDataTask = session.dataTask(with: request as URLRequest) { (data, response, error) -> Void in
// Get the HTTP status code of the request.
let statusCode = (response as! HTTPURLResponse).statusCode
if statusCode == 200 {
// Convert the received JSON data into a dictionary.
do {
if let dataDictionary = (try? JSONSerialization.jsonObject(with: data!, options: [JSONSerialization.ReadingOptions.mutableContainers])) as? [String:Any] { let accessToken = dataDictionary["access_token"] as? String }
UserDefaults.setObject(accessToken, forKey: "LIAccessToken")
UserDefaults.standard.synchronize()
DispatchQueue.main.async(execute: { () -> Void in
self.dismiss(animated: true, completion: nil)
})
}
catch {
print("Could not convert JSON data into a dictionary.")
}
}
new Code: ( this is from app coda that is not able to compile in latest swift,https://github.com/appcoda/LinkedInSignInDemo/blob/master/LISignIn/WebViewController.swift)
let dataDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers)
let accessToken = dataDictionary["access_token"] as! String
NSUserDefaults.standardUserDefaults().setObject(accessToken, forKey: "LIAccessToken")
NSUserDefaults.standardUserDefaults().synchronize()
dispatch_async(dispatch_get_main_queue(), { () -> Void in
self.dismissViewControllerAnimated(true, completion: nil)
})

Answer 1

You have to use like this :
You defined accessToken in if loop. And you are accessing it outside of it.
if let dataDictionary = (try? JSONSerialization.jsonObject(with: data!, options: [JSONSerialization.ReadingOptions.mutableContainers])) as? [String:Any] {
let accessToken = dataDictionary["access_token"] as? String
UserDefaults.setObject(accessToken, forKey: "LIAccessToken")
}