swift - 循环引用问题

// 1.创建类
class Person {
var name : String = ""
var book : Book?

deinit {
print("Person -- deinit")
}
}

class Book {
var price : Double = 0
/*
OC中表示弱引用
__weak/__unsafe_unretained(野指针错误)
Swift中表示弱引用
weak/unowned(野指针错误)
*/
// weak var owner : Person?
// unowned 不能用于修饰可选类型
unowned var owner : Person = Person()

deinit {
print("Book -- deinit")
}
}

// 2.创建两个对象
var person : Person? = Person()
person!.name = "why"
var book : Book? = Book()
book!.price = 60.0

person!.book = book
book!.owner = person!

person = nil
book = nil