Dictionary in swift 3.0 giving nil when tried to add a dict

Question

var dist: Dictionary<String, NSObject>!
var bigDist : Dictionary<String, Dictionary<String, NSObject>>!

self.bigDist["1" as String] = self.dist

When I try to do this, I get an error:

fatal error: unexpectedly found nil while unwrapping an Optional value

Data set for self.dist:

Optional(["hits": 0, "name": India lags behind China in consumer spends: Stefano Ricci’s Jackie Manglani, "web": Livemint, "id": -1655, "like": 0, "iurl": http://www.livemint.com/rf/Image-222x148/LiveMint/Period2/2017/02/21/Photos/Processed/jackiemanglani2-kXhC--621x414@LiveMint.JPG, "notify": 0, "date": 201655200217, "active": 1, "type": Mark, "dateAdded": 20/02/2017, "url": http://www.livemint.com/Consumer/3NT8Vbw7BcGeoPJNMoyK5H/India-lags-behind-China-in-consumer-spends-Stefano-Riccis.html])

Answer 1

Your variable bigDist is an implicitly unwrapped optional. (You declare it with) your_type!.

That means that:

1. It can contain a nil.
2. You don't need to unwrap it using ? or !.
3. If you reference it and it contains nil, you'll crash.

Number 3 is what's happening.

You need to create an empty dictionary. Try getting rid of the ! in the declaration, and creating an empty dictionary when you declare it:

var bigDist : Dictionary<String, Dictionary<String, NSObject>> = [:]

Answer 2

You did not initialize bigDist:

var dist: Dictionary<String, NSObject>? = nil
var bigDist = Dictionary<String, Dictionary<String, NSObject>>()

self.bigDist["1"] = self.dist

---

The code could be swiftier anyway. Using [String: NSObject] instead of Dictionary<String, NSObject> (which is exactly the same) makes the code easier to read and can prevent such a mistake like you did.

var dist: [String: NSObject]? = nil
var bigDist = [String: [String: NSObject]]()

self.bigDist["1"] = self.dist