Static string constant in swift evaluating as empty string ""

Question

Why does my string constant kAppCacheKey evaluate to an empty string the first time I access it? It shows up as the string "myAccount" on subsequent calls to it.

Am I declaring static constants in the right way?

let kAppCacheKey = "myAccount"
class LoggedUser {

    class var sharedInstance: LoggedUser {
        struct Static {
            static let instance = LoggedUser.loadFromCache()
        }
        return Static.instance
    }

    override private init() {
        super.init()
    }


    private class func loadFromCache() -> LoggedUser {
       //kAppCacheKey is evaluated as an empty string here for some reason
       if let data = Locksmith.loadDataForUserAccount(kAppCacheKey) as? [String:String]
       {
       }
    }