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iOS Build a Weather App with Swift (Retired) Concurrency Using Our JSON Data

1,594 Points

Unexpectedly found nil while unwrapping an optional value

This is the code I'm using and for some reason the console displays the title of this post.

 private let apiKey = ""//32 letters and numbers

    override func viewDidLoad() {
        // Do any additional setup after loading the view, typically from a nib.
        let baseURL = NSURL(string: "https://api.forecast.io/forecast/\(apiKey)")
        let forecastURL = NSURL(string: "37.8267,-122.423", relativeToURL : baseURL)

        let sharedSession = NSURLSession.sharedSession()
        let downloadTask : NSURLSessionDownloadTask = sharedSession.downloadTaskWithURL(forecastURL!, completionHandler: { (location: NSURL!, response: NSURLResponse!, error: NSError!) -> Void in

            if (error == nil) {

                let dataObject = NSData(contentsOfURL: location)
                let weatherDictionary : NSDictionary = NSJSONSerialization.JSONObjectWithData(
                    dataObject!, options: nil, error: nil) as! NSDictionary




The error seems to come from the weatherDictionary. Thanks for any help.

2 Answers

Caleb Kleveter
Caleb Kleveter
Treehouse Moderator 37,862 Points

I believe you are supposed to us an "if-let" statement instead of a !.

1,594 Points

how would I go about changing it to "if let" the correct way? When I tried it told me the data type was not convertible or something.