Cannot invoke 'value' with an argument list of type '(String)'

You probably need to change them to (message as AnyObject).value(forKey:"···") (adding the forKey: label).

Do you know what kind of object message is supposed to be? Repeatedly casting it to AnyObject is odd. It would be cleaner to create a new variable - let messageObject = message as AnyObject and then call messageObject.value(forKey:"···"). (I suspect you really want to cast it to Dictionary or something like that, in which case you can do messageDictionary["···"] instead of calling value(forKey:).)

Also, in Swift you can do this to reduce redundancy even more:

if let content = messageObject.value(forKey:"content") as? String {
  stringContent = content
}