In Xcode6 Beta4 was added Access Control to Swift.

private entities can only be accessed from within the source file where they are defined.!
internal entities can be accessed anywhere within the target where they are defined.!
public entities can be accessed from anywhere within the target and from any other context that imports the current target’s module.!

By defaul is used internal access control.

private func id() {
  //code here
public func fullName () {
  //code here

internal func debugState () {
  //code here

We can also set acess control to the properties. You can make a get of a property to be more accessible than its set.

 private var id: String
 private(set) var type: String

Swift Access Control is in development at the moment. It's not perfect yet. I'm looking forward to see how it will be improved

Read more about Access Control on Apple Swift blog.
On Apple Devforums is a great discussion this new feature.