保留循环关闭

Question

我尝试实现 Coordinator 模式的一些变体，但我在关闭时遇到了保留循环的问题。它看起来像这样：

func goTo() {
    let coord = SecondViewCoordinator(nav: navigationController)
    add(coord)
    coord.start()
    coord.deinitIfNeeded = { [weak self] in
        guard let self = self else { return }
        self.free(coord)
    }
}

如您所见，我设置deinitIfNeeded然后，如果在SecondViewCoordinator调用中deinitIfNeeded?()控制器正确弹出，但SecondViewCoordinator即使childCoordinators数组为空，对is 的引用仍然存在。

我的 Coordinator 类看起来像这样：

func goTo() {
    let coord = SecondViewCoordinator(nav: navigationController)
    add(coord)
    coord.start()
    coord.deinitIfNeeded = { [weak self] in
        guard let self = self else { return }
        self.free(coord)
    }
}

内存图显示：

有任何想法吗？

Answer 1

In

coord.deinitIfNeeded = { [weak self] in
    guard let self = self else { return }
    self.free(coord)
}

You are holding a strong reference to coord inside the closure. Try something like this;

coord.deinitIfNeeded = { [weak self, weak coord] in
    guard let self = self, let coord = coord else { return }
    self.free(coord)
}

The memory graph is giving a hint that this is the case (the right side says the strong reference is in a closure).

You could also set coord.deinitIfNeeded to nil inside the closure.