NSMutableDictionary treats NSString value as NSNumber

Question

I have the following value in a NSMutableDictionary - see image

I'm attempting to get at "a" thus:

let a = dictionary.objectForKey("a") as! String

the app crashes at this point with

Could not cast value of type '__NSCFNumber' (0x...) to 'NSString' (0x...).

other numbers inside "" are treated as strings as are numbers outside of strings cast to String without any issue.

Can anyone let me know what's going on? And how to get at these values easily?

Answer 1

The value is an NSNumber, not an NSString. You can use stringValue to convert it:

if let a = d["a"] as? NSNumber {
    let aString = a.stringValue
    println(aString) // -1
} else {
    // either d doesn't have a value for the key "a", or d does but the value is not an NSNumber
}

If you're sure it exists and is an NSNumber, you can use forced unwrapping, forced casting, and string interpolation:

let a = d["a"]! as! NSNumber
let aString = "\(a)"