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)?

“... 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
– Rob, Commented Aug 27, 2020 at 5:24
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
– Asperi, Commented Aug 27, 2020 at 6:47

Roman Ryzhiy · Accepted Answer · 2020-08-27 06:30:37Z

0

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

answered Aug 27, 2020 at 6:30

Roman Ryzhiy

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2 Comments

David Pasztor Over a year ago

This approach is unnecessarily overcomplicated. See the linked duplicate for a much clearer solution.

Roman Ryzhiy Over a year ago

@DávidPásztor This "unnecessarily overcomplicated" approach can be inherited. You cannot say this about the "much clearer solution".

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