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:
@property(strong)...
@property(weak)...
如何快速完成?
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") }
}
默认情况下,属性为强。但是看看“公寓”类的租户属性,它被宣布为弱项。您还可以使用无主关键字,该关键字从Objective-C转换为unsafe_unretained
https://itunes.apple.com/tr/book/swift-programming-language/id881256329?mt=11
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