在添加到容器視圖控制器/從容器視圖控制器中刪除時，如何為子視圖控制器設置動畫？

Question

我有以下2個函數，用於添加和刪除從容器視圖控制器觸發的子視圖控制器：

@discardableResult func addChildViewController(withChildViewController childViewController: UIViewController) -> UIViewController {
    // Add Child View Controller
    addChildViewController(childViewController)
    childViewController.beginAppearanceTransition(true, animated: true)
    // Add Child View as Subview
    view.addSubview(childViewController.view)
    // Configure Child View
    childViewController.view.frame = view.bounds
    childViewController.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    // Notify Child View Controller
    childViewController.didMove(toParentViewController: self)
    return childViewController
}
@discardableResult func removeChildViewController(withChildViewController childViewController: UIViewController) -> UIViewController {
    // Notify Child View Controller
    childViewController.willMove(toParentViewController: nil)
    childViewController.beginAppearanceTransition(false, animated: true)
    // Remove Child View From Superview
    childViewController.view.removeFromSuperview()
    // Notify Child View Controller
    childViewController.removeFromParentViewController()
    return childViewController
}

上面的函數是UIViewController的擴展，所以我要做的就是父視圖控制器上的self.addChildViewController（）和self.removeChildViewController（）。

我該如何為在離開視圖時刪除的視圖和在進入視圖時添加的視圖設置動畫？

Answer 1

在不同的子視圖控制器之間進行動畫處理：-

func cycleFromViewController(oldViewController: UIViewController, toViewController newViewController: UIViewController) {
    oldViewController.willMove(toParentViewController: nil)
    newViewController.view.translatesAutoresizingMaskIntoConstraints = false

    self.addChildViewController(newViewController)
    self.addSubview(subView: newViewController.view, toView:self.containerView!)

    newViewController.view.alpha = 0
    newViewController.view.layoutIfNeeded()

    UIView.animate(withDuration: 0.5, delay: 0.1, options: .transitionFlipFromLeft, animations: { 
        newViewController.view.alpha = 1
        oldViewController.view.alpha = 0
    }) { (finished) in
        oldViewController.view.removeFromSuperview()
        oldViewController.removeFromParentViewController()
        newViewController.didMove(toParentViewController: self)
    }
}

在上面，

• oldViewController：-當前顯示的子viewController
• newViewController：-將要添加的新子視圖控制器
• containerView：-顯示所有子控制器的視圖。

若要設置子視圖的動畫，可以根據需要通過將transitionFlipFromLeft替換為可用的UIViewAnimationOptions來使用不同類型的動畫樣式。

Answer 2

Sagar的答案不完整，那里缺少addSubview方法

這是完整答案

func cycleFromViewController(oldViewController: UIViewController, toViewController newViewController: UIViewController) {
        oldViewController.willMove(toParentViewController: nil)
        newViewController.view.translatesAutoresizingMaskIntoConstraints = false

        self.addChildViewController(newViewController)
        self.addSubview(subView: newViewController.view, toView:self.containerView!)

        newViewController.view.alpha = 0
        newViewController.view.layoutIfNeeded()

        UIView.animate(withDuration: 0.5, delay: 0.1, options: .transitionFlipFromLeft, animations: {
            newViewController.view.alpha = 1
            oldViewController.view.alpha = 0
        }) { (finished) in
            oldViewController.view.removeFromSuperview()
            oldViewController.removeFromParentViewController()
            newViewController.didMove(toParentViewController: self)
        }
    }

    //--------------------------------------------------------------------------------


   private func addSubview(subView:UIView, toView parentView:UIView) {
        self.view.layoutIfNeeded()
        parentView.addSubview(subView)

        subView.leadingAnchor.constraint(equalTo: parentView.leadingAnchor).isActive = true
        subView.topAnchor.constraint(equalTo: parentView.topAnchor).isActive = true
        subView.bottomAnchor.constraint(equalTo: parentView.bottomAnchor).isActive = true
        subView.trailingAnchor.constraint(equalTo: parentView.trailingAnchor).isActive  = true
    }

希望對別人有幫助