class level or struct level method in swift like static method in Java?

Question

Is there a way to add method at class level or struct level in swift?

struct Card {
    var rank: Rank
    var suit: Suit
    func simpleDescription() -> String {
        return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"
    }
}

Excerpt From: Apple Inc. “The Swift Programming Language.” iBooks. https://itun.es/us/jEUH0.l

Now if you wanted to add a method that creates a full deck of cards, what would be the best way to accomplish it?

score 91 · Answer 1 · answered Jun 08 '14 at 19:11

91

To add a type-level method in a class, add the class keyword before the func declaration:

class Dealer {
    func deal() -> Card { ... }
    class func sharedDealer() -> Dealer { ... }
}

To add a type-level method in a struct or enum, add the static keyword before the func declaration:

struct Card {
    // ...
    static func fullDeck() -> Card[] { ... }
}

Both are generally equivalent to static methods in Java or class methods (declared with a +) in Objective-C, but the keyword changes based on whether you're in a class or struct or enum. See Type Methods in The Swift Programming Language book.

answered Jun 08 '14 at 19:11

rickster

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This has been updated in 6.3, for what it's worth: http://adcdownload.apple.com//Developer_Tools/Xcode_6.3_beta/Xcode_6.3_beta_Release_Notes.pdf Cheers – Chris Conover Feb 11 '15 at 00:50
Classes have both "static" and "class" funcs. See following answer for explanation http://stackoverflow.com/a/29636742/2774520 – Oleksii Nezhyborets Aug 13 '16 at 21:49

score 31 · Answer 2 · answered Jun 08 '14 at 18:59

31

In Struct:

struct MyStruct {
    static func something() {
        println("Something")
    }
}

Called via:

MyStruct.something()

In Class

class MyClass {
    class func someMethod() {
        println("Some Method")
    }
}

called via:

MyClass.someMethod()

answered Jun 08 '14 at 18:59

Logan

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3

@IrshadQureshi - there's many differences, the most important in my mind is that structs are ValueType and classes are ReferenceType – Logan Feb 04 '16 at 16:15
2

@IrshadQureshi And structs can't be extended like classes – MadProgrammer Mar 25 '16 at 12:01
subclasses can override class func's which is not possible with static methods. – tapmonkey Jun 07 '18 at 07:46

score 8 · Answer 3 · answered Jun 08 '14 at 18:53

8

p 353

class SomeClass {
    class func someTypeMethod() {
        // type method implementation goes here
    }
}
SomeClass.someTypeMethod()

Excerpt From: Apple Inc. “The Swift Programming Language.” iBooks. https://itun.es/us/jEUH0.l

answered Jun 08 '14 at 18:53

Gene De Lisa

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class level or struct level method in swift like static method in Java?

3 Answers3

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