awkward

var iExist:String?

var s:[String:Any] = [String:Any]()
s["thing"] = 2
if let x = s["thing"] {
    iExist = x
}


// explicit cast x

if let x:String = s["thing"] {
    iExist = x
}

// which leaves me with

if let x:String = s["thing"] as? String {
    iExist = x
}