Is there a Kotlin equivalent `object` in Swift? [duplicate]

Question

In Kotlin we can compose a Singleton object using

object MySingleton {
    // Some static variable.
}

without need to have a class and control its constructor to be private etc.

I try to search if there's equivalent Object in Swift language I can leverage, or I need to do my own Singleton class instance (e.g. private init() and static)?

Answer 1

It's a task of "make and forget" type. Just create the class and use it everywhere you need a singleton:

class Singleton {
    private static var uniqueInstance: Singleton?
    
    public static var instance: Singleton {
        if Singleton.uniqueInstance == nil {
            Singleton.uniqueInstance = self.init()
        }
        
        return Singleton.uniqueInstance!
    }

    required init() {}
}

class MyClass : Singleton {
    var param: Int = 0
}

let instanceOfMyClass: MyClass = MyClass.instance as! MyClass
print(instanceOfMyClass.param) // prints 0

instanceOfMyClass.param = 5

let anotherInstanceOfMyClass: MyClass = MyClass.instance as! MyClass
print(anotherInstanceOfMyClass.param) // prints 5