How does "public private(set)" access modifiers work?

Question

So I'm going through the Apple docs here - Apple Docs

Then I ran into this:

public struct TrackedString {
    public private(set) var numberOfEdits = 0
    public var value: String = "" {
        didSet {
            numberOfEdits += 1
        }
    }
    public init() {}
}

How does adding public private(set) exactly work? If you can show some easier examples/explanation that would be amazing!

Answer 1

This just means that the getter for numberOfEdits is public, but the setter is private. There's nothing more to it.

The reason in this case is so that you can read numberOfEdits publicly, but you can only set it via changing value. If it were fully public, then anyone could set it, but if it were only settable, then the didSet in value couldn't modify it. private(set) is a compromise between those two.

Answer 2

This property can be read, but cannot be set from the outside.

You assign a lower access level by writing private(set).

Its works like Public getter and Private setter.

//MARK:- Foo
class Foo {
    private var name: String
    private var ID: String

   //initialize
   init(name:String, ID:String){
      self.name = name
      self.ID = ID
   }
}

We will get an error when to try to access private variable.

But we can fix this error in a single line by changing private access level to private(set).

//MARK:- Foo
class Foo {
    private(set) var name: String
    private var ID: String

   //initialize
   init(name:String, ID:String) {
       self.name = name
       self.ID = ID
   }
}

So you can easy access the private variable, constant, property, or subscript.

//Access class value from Foo
let fooObjc = Foo.init(name: "test", ID: "9900")
print(fooObjc.name)

Use fileprivate(set), private(set), and internal(set) to change the access level of this synthesized setter in exactly the same way as for an explicit setter in a computed property.

This property can be read, but cannot be set from the outside.

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