How to unwrap optional value from NSDictionary? - Swift [duplicate]

Question

I'm trying to unwrap these Int values that I receive from the server, but everything I've tried it just doesn't work. It keeps printing:

"Optional(int value)".

var playerId, roomId : Int!

func makeGetRequest(path: String){
    let urlPath: String = "http://myServer.ddns.net:7878/\(path)"
    let url: NSURL = NSURL(string: urlPath)!
    var request1: URLRequest = URLRequest(url: url as URL)

    request1.httpMethod = "GET"
    let queue:OperationQueue = OperationQueue()

    NSURLConnection.sendAsynchronousRequest(request1 as URLRequest, queue: queue, completionHandler:{ (response: URLResponse?, data: Data?, error: Error?) -> Void in

        do {
            let jsonData = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as! NSDictionary
            print("ASynchronous\(jsonData)")

            self.playerId = jsonData.value(forKey: "playerId") as! Int
            self.roomId = jsonData.value(forKey: "roomId") as! Int

           print("\(self.roomId)   \(self.playerId)")

        } catch let error as NSError {
            print(error.localizedDescription)
        }

    })
}

enter image description here

All of those ! - my eyes! Make it stop. Seriously, you do know that your code is going to crash due to the misuse of the ! operator, right? Please spend some quality time reading up on optionals and safe unwrapping in the Swift book. — rmaddy
– rmaddy, Commented Mar 11, 2017 at 1:52
Nothing else worked, I just copy paste this last try and yes I know it isn't good at all. if let a = jsonData.value(forKey: "roomId") as! Int this was the previous try — Sorin
– Sorin, Commented Mar 11, 2017 at 1:56

Parth Adroja · Accepted Answer · 2017-03-11 02:30:39Z

1

Avoid using ! directly because if the value is nil and you try to access it will crash the application. So the best way to do it is either use if let or guard let statements. For example check below:

self.playerId = jsonData.value(forKey: "playerId") as! Int
self.roomId = jsonData.value(forKey: "roomId") as! Int

if let safePlayerID = self.playerId, let saferoomID = self.roomId {
     print("\(safePlayerID)   \(saferoomID)")
}

Using guard let:

guard let safePlayerID = self.playerId, let saferoomID = self.roomId else {
      return nil
}

print("\(safePlayerID)   \(saferoomID)")

answered Mar 11, 2017 at 2:30

Parth Adroja

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Comments

ghostatron · Accepted Answer · 2017-03-11 02:22:01Z

0

That's how optionals print. If you don't want that, then you have to unwrap them before printing them. Keep in mind that the comments on your question are valid, and the "!" will almost certainly crash you at some point. But just for brevity, you can do this:

print("\(self.roomId!)   \(self.playerId!)")

answered Mar 11, 2017 at 2:22

ghostatron

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3 Comments

Sorin Over a year ago

Thanks a lot! This was the fix I needed, now I can use those values :)

rmaddy Over a year ago

This is a bad idea. This will crash if those values aren't set. The answer by Party is much, much better than slapping on !.

ghostatron Over a year ago

So you downvote me because you disagree with what is still a correct solution. And you also basically repeated exactly what I stated in my answer. Gee, thanks. And at least I explain WHY he's seeing what he's seeing.

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