Swift 中的强引用和弱引用 [英] Strong and weak references in Swift

问题描述

在 Objective C 中，您可以将属性定义为具有强引用或弱引用，如下所示:

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

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

这是如何快速完成的?

推荐答案

直接来自 Swift 语言指南:

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") }
}

属性默认是强的.但是看看公寓"类的租户属性，它被声明为弱.你也可以使用 unowned 关键字，它从 Objective-C 转换为 unsafe_unretained

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

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