Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

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

Posted by Ezekiel Elin
Ezekiel Elin
3,839 Points

Unable to use NSJSONSerialization

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

Error:

http://i.imgur.com/wRPZmjo.png

1 Answer

Ben Griffith
Ben Griffith
5,808 Points
Ben Griffith
Ben Griffith
5,808 Points

Are you unwrapping your optional (dataObject)? Notice the ! at the end of the variable dataObject's initialisation.

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

You could also do it while setting your weatherDictionary constant

let weatherDictionary: NSDictionary = 
NSJSONSerialization.JSONObjectWithData(dataObject!, options: nil, error: nil) as 
NSDictionary
Elijah Gartin
Elijah Gartin
13,182 Points
Elijah Gartin
Elijah Gartin
13,182 Points

Thank you.

Do you know if there is a best practice in terms of unwrapping?

It seems like the second way you wrote it has been the standard thus far in the fixes that came with XCode 6.1...