Class level variable set always nil why?

Question

I am always getting nil when trying to assign any string to class level variable.

Below is my console output:

// test = nil
// Demo.test = nil

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        Demo.test = "app"
        print("Demo.test = \(Demo.test)")
    }
}

class Demo {

    class var test: String? {
        set {
            UserDefaults.standard.set(test, forKey: "test")
            print("test = \(test)")
        }
        get {
            return UserDefaults.standard.string(forKey: "test")
        }
    }
}

Answer 1

When you call test inside the setter, the getter is called to get the value of test. At this point, the value for "test" is nil inside UserDefaults. So instead of storing test, you should using newValue which is the value that you are about to set to the variable.

class Demo {

    class var test: String? {
        set {
            UserDefaults.standard.set(newValue, forKey: "test")
            print("test = \(test)")
        }
        get {
            return UserDefaults.standard.string(forKey: "test")
        }
    }

}

---

From the docs,

If a computed property’s setter does not define a name for the new value to be set, a default name of newValue is used.

Check the ComputedProperties section in Properties to understand how getters and setters work.