Unexpectedly found nil

Question

I guess this is basic Swift, so I'm a bit embarrassed to ask:

In my app, I download a plist file from a server as such:

 Alamofire.download(url, to: destination).response { response in
       if let url = response.destinationURL {
                    self.holidays = NSDictionary(contentsOf: url)!
                }
            }

The file is a valid file, and it is succesfully dowloaded and sitting physically in my Documents folder.

However, the app crashes on

self.holidays = NSDictionary(contentsOf: url)!

saying

Fatal error: Unexpectedly found nil while unwrapping an Optional value

What gives?

`NSDictionary(contentsOf: url)` can return `nil` which would trigger that crash. You may want to check the file actually exists first and/or adjust the path if needed. — CodingNagger, Oct 23 '18 at 11:18
Can we assume that you already read [What does “fatal error: unexpectedly found nil while unwrapping an Optional value” mean?](https://stackoverflow.com/questions/32170456/what-does-fatal-error-unexpectedly-found-nil-while-unwrapping-an-optional-valu) — Martin R, Oct 23 '18 at 11:25
Well, then you know the forced unwrapping crashes if `NSDictionary(contentsOf: url)` is nil – did you investigate that possibility? — Martin R, Oct 23 '18 at 11:29
Possible duplicate of [What does "fatal error: unexpectedly found nil while unwrapping an Optional value" mean?](https://stackoverflow.com/questions/32170456/what-does-fatal-error-unexpectedly-found-nil-while-unwrapping-an-optional-valu) — Desdenova, Oct 23 '18 at 11:34

score 1 · Accepted Answer · answered Oct 23 '18 at 11:27

1

Your NSDictionary is failing to initialize, so when you try to force unwrap it (with the exclamation mark) it fails and crashes.

answered Oct 23 '18 at 11:27

Oni_01

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score 0 · Answer 2 · answered Oct 23 '18 at 11:40

Try something like this:

if let dictionary = NSDictionary(contentsOf: url) {
    self.holidays = dictionary
}

Alternatively you can use the guard statement:

guard let dictionary = NSDictionary(contentsOf: url) else {
    print("NSDictionary failed to initialise")
    return
}

self.holidays = dictionary

Unexpectedly found nil

2 Answers2