ios - Swift 4 覆盖 func viewDidAppear(_ 动画 : Bool) not triggering when i dissmiss viewcontroller

Question

我有一个 viewControllerA，它以编程方式在 Storyboard中呈现，没有 segue，如下所示:

let storyboard = UIStoryboard(name: "IdStoryBoard", bundle: nil)
let controller = storyboard.instantiateViewController(withIdentifier: "idcontroller") as! BController
self.present(controller, animated: true, completion: nil) 

然后从 viewControllerA 我转到 viewControllerB，使用 Storyboard segue。

当我关闭 viewControllerB self.dismiss(animated: true, completion: nil) 时，viewControllerA 中未触发 viewDidAppear .

Answer 1

如果您想在关闭 viewControllerB 时触发 viewControllerA 中的事件，我建议创建一个委托(delegate)方法来链接两者。

在您的viewControllerA 上包含以下内容:

protocol TriggerEventDelegate {
    func eventToBeTriggered();
}

然后使您的viewControllerA 符合该协议(protocol):

extension AController: TriggerEventDelegate {
    func eventToBeTriggered() {
         // Implement whatever you want to trigger here
    }
}

在您的viewControllerB上，创建一个委托(delegate)引用:

class BController: UIViewController {
    weak var delegate: TriggerEventDelegate? 
}

在您关闭 viewControllerB 时执行触发:

func dismiss() {
    delegate?.eventToBeTriggered()
    self.dismiss(animated: true, completion: nil)
}

最后但并非最不重要的，当从 viewControllerA 移动到 viewControllerB 时，将您的 delegate 设置为 viewControllerA :

func pushFromAToB() {
    let storyboard = UIStoryboard(name: "IdStoryBoard", bundle: nil)
    let controller = storyboard.instantiateViewController(withIdentifier:     "idcontroller") as! BController
    controller.delegate = self
    self.present(controller, animated: true, completion: nil) 
}

您的事件现在将被正确触发，而无需依赖 viewDidAppear