Q:

Cannot call value of non-function type '((AnyObject) -> AnyObject?)!' - Swift 3

I am trying to convert my current project to Swift 3 and am running into problems regarding the objectForKey to objectFor conversion.
The type of myData is AnyObject
Before:
let x = myData.objectForKey('myKey')

Now:
let x = myData.objectFor('myKey') // not working.

In the second case, XCode gives me error Cannot call value of non-function type '((AnyObject) -> AnyObject?)!' which I have no idea how to fix.
Does anyone know how to updated the objectForKey method and why this conversion is not working?
Other Example:
I created another example in a playground to reproduce this issue. The lines of code used are pasted below. The outcome of running this is the same error as stated above.
var x: AnyObject = ["Hello" : "Goodbye"] as AnyObject
x.objectFor("Hello")

A:

The syntax has changed from:
let x = myData.objectForKey("myKey")

to:
let x = myData.object(forKey:"myKey")

in Swift 3.
Example:
var x : AnyObject = ["Hello" : "Goodbye"] as AnyObject
x.object(forKey:"Hello")

