swift - UIViewController 不取消初始化(mvvm + 协调器)

Question

因为这个问题，我很头疼。为什么我的 SplashscreenViewController 没有取消初始化？你们在下面发布的代码中看到任何潜在的保留周期了吗？我试图检查 Malloc 堆栈，但找不到任何有用的信息。

final class SplashscreenViewController: UIViewController {
    var viewModel: SplashscreenViewModelType!

    private let animationStartScale: CGFloat = 0.75
    private let animationEndScale: CGFloat = 1.0
    private let animationDuration: TimeInterval = 0.4

    private let splashscreenDuration: TimeInterval = 1.5

    @IBOutlet private weak var logoImageView: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()

        animateLogo(scale: animationStartScale)
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        DispatchQueue.main.asyncAfter(deadline: .now() + splashscreenDuration, execute: { [weak self] in
            self?.viewModel.onFinish.onNext(())
        })
    }

    private func animateLogo(scale: CGFloat) {
        UIView.animate(withDuration: animationDuration, animations: {
            self.transformImage(scale: scale)
        }, completion: { _ in
            if scale == self.animationStartScale {
                self.animateLogo(scale: self.animationEndScale)
            } else {
                self.animateLogo(scale: self.animationStartScale)
            }
        })
    }

    private func transformImage(scale: CGFloat) {
         logoImageView.transform = CGAffineTransform(scaleX: scale, y: scale)
    }
}

持有 SplaschreenViewController 实例的类是它的协调器。代码如下:

final class SplashscreenCoordinator: BaseCoordinator {
    private let window: UIWindow

    init(window: UIWindow) {
        self.window = window
    }

    override func start() -> Observable<Void> {
        let vc: SplashscreenViewController = SwinjectStoryboard.instantiateInitialViewController()
        window.rootViewController = vc
        window.makeKeyAndVisible()

        let onFinish = vc.viewModel.onFinish
            .asObservable()
            .flatMap { [unowned self] _ -> Observable<Void> in
                guard self.window.rootViewController == vc else {
                    return Observable<Void>.empty()
                }
                if UserPreferencesManager.isLoggedIn() {
                    return self.startAppForLoggedInUser()
                } else {
                    return self.startAppForAnonymousUser()
                }
            }

        return onFinish
    }

    private func startAppForLoggedInUser() -> Observable<Void> {
        let tabBar = TabBarCoordinator(window: window)
        return coordinate(to: tabBar)
    }

    private func startAppForAnonymousUser() -> Observable<Void> {
        let startCoordinator = StartCoordinator(window: window)
        return coordinate(to: startCoordinator)
    }
}

还有一些来自 BaseCoordinator 的代码:

...
private func store(coordinator: BaseCoordinator) {
    childCoordinators[coordinator.identifier] = coordinator
}

private func free(coordinator: BaseCoordinator) {
    childCoordinators[coordinator.identifier] = nil
}

func coordinate(to coordinator: BaseCoordinator) -> Observable<Void> {
    store(coordinator: coordinator)
    return coordinator.start()
        .do(onNext: { [weak self] _ in
            self?.free(coordinator: coordinator)
        })
}
...

预先感谢您的回答!

Answer 1

我可以看到如何阻止 SplashscreenViewController 释放的两种方法如下:

1. 如果它是 rootViewController 的 window 没有被释放。请记住，应用程序会保留关键窗口。
2. 在您的start() 函数中，Observable 闭包保留了vc 变量。此 Observable 可能会保留在别处，无论是显式保留还是在 DisposeBag 中。