swift - deinit 没有被调用。帮我解决这个问题

Question

class MyClass {
    func greeting() {
        answer += "Hello, World!"
    }
}

class Handler {
    var closure: (() -> Void)?
    let obj = MyClass()
    
    func setupClosure() {
        closure = {
            self.obj.greeting()
        }
    }
    
    deinit {
        answer += "Handler is being deinitialized."
    }
}

var answer: String = ""
func handlerDeinitialization() -> String {
    var handler: Handler? = Handler()
    handler!.setupClosure()
    handler!.closure!()
    handler = nil
    return answer
}

print(handlerDeinitialization())

我的预期答案是“Hellow，World！处理程序正在被取消初始化。” 如何解决这个问题？我只想更改一行代码，而不是整个代码。

Answer 1

改写：

    closure = { [weak self] in
        if let self = self {
            self.obj.greeting()
        }
    }

（请注意，我更改了不止一行。但我的回答是如何通过仅更改一行来做到这一点的巨大线索。）

Answer 2

closure = { [unowned self] in
        self.obj.greeting()
}

对于一条线解决方案