Swift 不取消初始化实例

Question

我有以下代码:

class Company {
    let name: String
    var founder: Person?

    init(name: String) {
        self.name = name
        print("\(self.name) was initialized")
    }

    deinit {
        print("\(self.name) was deinitialized")
    }
}

class Person {
    let name: String
    weak var company: Company?

    init(name: String) {
        self.name = name
        print("\(self.name) was initialized")
    }

    deinit {
        print("\(self.name) was deinitialized")
    }
}

var mark: Person?
var facebook: Company?

mark = Person(name: "Mark Zuckerberg")
facebook = Company(name: "Facebook")
mark!.company = facebook
facebook!.founder = mark

facebook = nil
mark = nil

我对 person 的引用很弱，但它似乎仍然存在一个保留周期，因为这些实例都没有被取消初始化。它打印出初始化语句，但不打印取消初始化语句。

输出:

Mark Zuckerberg was initialized
Facebook was initialized

Answer 1

对于此示例，如果您使用可选链接分配对象变量并在代码块中实例化它们，则当没有对该对象的 strong 引用时，它们将被取消初始化。 ARC Documentation

class Company {
    let name: String
    var founder: Person?

    init(name: String) {
        self.name = name
        print("\(self.name) was initialized")
   }

    deinit {
        print("\(self.name) was deinitialized")
    }
}

class Person {
    let name: String
    weak var company: Company?

    init(name: String) {
        self.name = name
        print("\(self.name) was initialized")
    }

    deinit {
        print("\(self.name) was deinitialized")
    }
}

do{
    var mark: Person?
    var facebook: Company?

    mark = Person(name: "Mark Zuckerberg")
    facebook = Company(name: "Facebook")
    mark?.company = facebook
    facebook?.founder = mark
}