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

Posted by M T
M T
Courses Plus Student 1,587 Points

Value of optional type NSURL? not unwrapped - Swift weather app issue

On line 23, it shows an error for the forcastURL argument (inside the downloadTask line). I get: "Value of optional type NSURL? not unwrapped: did you mean to use '!' or '?' "

I even downloaded the finished project (line 42) and I have the same issue - how do you fix this? I'm on Yosemite and Xcode 6.1

P.S. I looked at the other question, and there's no space in the Lat,Long.

3 Answers

Joakim Birger Lie
Joakim Birger Lie
12,367 Points
Joakim Birger Lie
Joakim Birger Lie
12,367 Points

I had the exact same problem. The fix turned out to be a difference in the syntax for NSData.

Instead of the suggested:

let weatherData = NSData.dataWithContentsOfURL(forecastURL, options: nil, error: nil)

Write:

let weatherData = NSData(contentsOfURL: forecastURL!, options: nil, error: nil)

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

thats because the videos are using xcode 6, not xcode 6.1. Some things in swift have changed in 6.1. you probably need to force unwrap the NSURL variable by placing a bang (!) after the variable name

Josuel Garcia
Josuel Garcia
6,069 Points

even with the bang it will build successful but a nil error will show up in the debug console

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

can you post the relevant code you are using like the line where you actually set the NSURL object

Cesar Aviles
Cesar Aviles
3,998 Points
Cesar Aviles
Cesar Aviles
3,998 Points

This builds for me but my response is nil in the output window, it's hello nil. I put the hello to confirm that's where the nil was coming from.

private let apiKey = "04d038cd665f17fa7727f70c7a5f0d3f"

override func viewDidLoad() {
    super.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 weatherData = NSData(contentsOfURL: forecastUrl!, options: nil, error: nil)
    println("hello \(weatherData)")

}