Read-only and non-computed variable properties in Swift

Question

I\'m trying to figure out something with the new Apple Swift language. Let\'s say I used to do something like the following in Objective-C. I have readonly prop

Answer 1

There are two basic ways of doing what you want. First way is by having a private property and and a public computed property which returns that property:

public class Clock {

  private var _hours = 0

  public var hours: UInt {
    return _hours
  }

}

But this can be achieved in a different, shorter way, as stated in the section "Access Control" of the "The Swift Programming Language" book:

public class Clock {

    public private(set) var hours = 0

}

As a side note, you MUST provide a public initialiser when declaring a public type. Even if you provide default values to all properties, init() must be defined explicitly public:

public class Clock {

    public private(set) var hours = 0

    public init() {
      hours = 0
    }
    // or simply `public init() {}`

}

This is also explained in the same section of the book, when talking about default initialisers.