Strong and weak references in Swift

67cherries picture 67cherries · Jun 3, 2014 · Viewed 36.5k times · Source

In Objective C you can define a property as having a strong or weak reference like so:

@property(strong)...
@property(weak)...

How is this done in swift?

Answer

Kaan Dedeoglu picture Kaan Dedeoglu · Jun 3, 2014

Straight from the Swift Language guide:

class Person {
    let name: String
    init(name: String) { self.name = name }
    var apartment: Apartment?
    deinit { println("\(name) is being deinitialized") }
}

class Apartment {
    let number: Int
    init(number: Int) { self.number = number }
    weak var tenant: Person?
    deinit { println("Apartment #\(number) is being deinitialized") }
}

properties are strong by default. But look at the tenant property of the class "Apartment", it is declared as weak. You can also use the unowned keyword, which translates to unsafe_unretained from Objective-C

https://itunes.apple.com/tr/book/swift-programming-language/id881256329?mt=11