Is there a Kotlin equivalent `object` in Swift?

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)?

“... or I need to do my own Singleton class instance (e.g. `private init()` and `static`)?” ... yep, that’s precisely how you do it. — Rob, Aug 27 '20 at 05:24
For those who are looking for examples in Apple SDK - open Foundation module, at least, and look for constants starting from `public static var`, eg `struct CocoaError`. — Asperi, Aug 27 '20 at 06:47

score 0 · Accepted Answer · answered Aug 27 '20 at 06:30

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

This approach is unnecessarily overcomplicated. See the linked duplicate for a much clearer solution. — Dávid Pásztor, Sep 01 '20 at 13:41
@DávidPásztor This "unnecessarily overcomplicated" approach can be inherited. You cannot say this about the "much clearer solution". — Roman Ryzhiy, Sep 01 '20 at 13:50

Is there a Kotlin equivalent `object` in Swift?

1 Answers1