删除 UIViewController 的正确方法

Question

我有一个settingsController，它是一个自定义的UINavigationController，它必须出现和消失。

它的 XIB 位于故事板中，由于其他管理目的，我必须使用 var settingsController 跟踪它。

主视图控制器：

class MainViewController: UIViewController {

    var settingsController : MySettingsNavigationController?

    func settingsButtonPressed () {
        let storyboard = UIStoryboard(name: "Main Storyboard", bundle: nil)
        self.settingsController = storyboard.instantiateViewController(withIdentifier: "Settings Navigation Controller") as? MySettingsNavigationController
        self.settingsController!.transitioningDelegate = self
        self.settingsController!.modalPresentationStyle = .custom
        self.present(self.settingsController!, animated: true, completion: nil)
    }

    //Settings View Controller Transition Methods
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let containerView = transitionContext.containerView
        let fromViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
        let toViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
        if(self.isSettingsPresenting == true) {
            toViewController!.view.alpha = 1;
            toViewController!.view.transform = CGAffineTransform(scaleX: 0.001, y: 0.001);
            toViewController!.view.center = self.settingsButton.center

            UIView.animate(withDuration: 0.5, delay: 0,
                           options: [.curveEaseIn], animations: { () -> Void in

                toViewController!.view.alpha = 1;
                toViewController!.view.transform = CGAffineTransform(scaleX: 1, y: 1);
                toViewController!.view.center = fromViewController!.view.center
                containerView.addSubview(toViewController!.view)

            }, completion: { (completed) -> Void in

                transitionContext.completeTransition(completed)

            })

        } else {
            UIView.animate(withDuration: 0.5, delay: 0,
                           options: [.curveEaseOut], animations: { () -> Void in

                fromViewController!.view.alpha = 0;
                fromViewController!.view.transform = CGAffineTransform(scaleX: 0.01, y: 0.01);
                fromViewController!.view.center = self.settingsButton.center

            }, completion: { (completed) -> Void in
                //Two lines below added later to test..
                fromViewController?.view.removeFromSuperview()
                fromViewController?.removeFromParentViewController()
                transitionContext.completeTransition(completed)
            })
        }
    }
}

设置导航控制器：

class MySettingsNavigationController:  UINavigationController, UINavigationControllerDelegate
{
    .....

    func closeButtonPressed (_ sender: UIButton!) {
        self.dismiss(animated: true, completion: {
            //Tried removing self in here...
        })
    }
}

问题：

当我打开settingsController 并关闭它时，settingsController 分配的内存永远不会被释放；不知何故，settingsController 没有被释放。

注意：

我不得不这样做：

1. 从情节提要启动视图控制器
2. 使用自定义动画过渡
3. 不使用自定义委托（因为我无法将委托写入 已经是UINavigationControllerDelegate。这本来可以给 我有机会回电给家长，MainViewController 准备好被移除

Answer 1

不知何故，settingsController 没有被释放

• var settingsController 看起来可能是罪魁祸首。
  将ViewController 作为var 对象持有是非常不鼓励。

由于其他管理目的，我必须使用 'var settingsController' 对其进行跟踪。

• 使用提供controller 相关属性数据或处理用户交互的sharedHelper-esque 类进行评估。
  
• 除了settingsButtonPressed（应该单独负责调用settingsController）之外，没有任何功能应该被设计成需要settingsController 的实例才能执行。此类功能所需的数据可以通过protocols、blocks、shared instances等多种方式提取。