使用一个动画关闭和呈现模态视图控制器

Question

问题是我不知道如何关闭和显示只有一个过渡动画的视图控制器。

我的故事板结构是：

我们可以说 A 控制器跟在 NavigationController 之后，B 是启动引用，C 是TabBar ViewController。 B 和 C 都以模态呈现 Cross Dissolve 过渡。

当用户登录到应用程序时（从 B），C 控制器会以模态方式显示 Flip水平 过渡。当用户注销时（从 C），B 以相同的方式呈现。在 A 控制器上，我根据用户是否已登录，直接转至 B 或 C .

我的问题是，如果我不从 B 或 C 中关闭以前的视图控制器，该控制器就会泄露。相反，如果我关闭它，A 会显示在目标控制器之前（B 或 C）已呈现。

是否可以仅显示 水平翻转 过渡并跳过 A 视图？

Answer 1

这是我用于解决此问题的解决方案。我不知道它如何与故事板集成，因为我不使用它们。

将此方法添加到 UIViewController 的类别中，然后可以在之前调用的任何地方调用 presentViewController:animated:completion。产生新控制器的无缝动画，同时仍然关闭前一个控制器。

-(void)presentViewControllerDismissingPrevious:(UIViewController* _Nonnull)controller animated:(BOOL)animated completion:(void (^ __nullable)(void))completion {

    UIViewController* visibleController = self;
    {
        UIViewController* temp;
        while( ( temp = visibleController.presentedViewController ) != nil ) {
            visibleController = temp;
        }
    }

    if( visibleController == self ) {
        // no previous controller to dismiss
        [self presentViewController:controller animated:animated completion:completion];
    } else {
        // create a temporary snapshot of the visible controller's entire window
        // and add to the current view controller's window until animation completed
        UIWindow* visibleWindow = visibleController.view.window;
        UIView* tempView = [visibleWindow snapshotViewAfterScreenUpdates:NO];
        UIView* rootView = self.view.window.subviews[0];
        tempView.frame = [rootView convertRect:visibleWindow.bounds fromView:visibleWindow];
        [rootView addSubview:tempView];

        [self dismissViewControllerAnimated:NO completion:^(){
            [self presentViewController:controller animated:animated completion:^(){
                [tempView removeFromSuperview];
                if( completion ) {
                    completion();
                }
            }];
        }];
    }
}

Answer 2

我对这个问题的解决方案是替换当前的 rootViewController，支持不同的转换：

static func replaceRootViewController(with viewController: UIViewController, transition: UIViewAnimationOptions, completion: (() -> ())? = nil) {        
    if transition == .transitionCrossDissolve {
        let overlayView = UIScreen.main.snapshotView(afterScreenUpdates: false)
        viewController.view.addSubview(overlayView)
        UIApplication.shared.keyWindow?.rootViewController = viewController

        UIView.animate(withDuration: 0.65, delay: 0, options: transition, animations: {
            overlayView.alpha = 0
        }, completion: { finished in
            overlayView.removeFromSuperview()
            if let completion = completion{
                completion()
            }
        })
    } else {
        _ = viewController.view
        UIView.transition(with: UIApplication.shared.keyWindow!, duration: 0.65,options: transition, animations: {
            UIApplication.shared.keyWindow?.rootViewController = viewController
        }){_ in
            if let completion = completion {
                completion()
            }

        }
    }
}

Answer 3

两个答案都非常有帮助，这里是 Swift 4 版本：

func presentHidingBehindScreenSnapshot(viewController: UIViewController,
                                     completion: (() -> (Void))? ) {
if let screenSnapshot = UIApplication.shared.keyWindow?.snapshotView(afterScreenUpdates: false),
  let rootViewController = UIApplication.shared.keyWindow?.rootViewController {
  rootViewController.view.addSubview(screenSnapshot)
  rootViewController.view.bringSubview(toFront: screenSnapshot)

  rootViewController.dismiss(animated: false, completion: {
    rootViewController.present(viewController, animated: false, completion: {
      screenSnapshot.removeFromSuperview()
      if let existingCompletion = completion {
        existingCompletion()
      }
    })
  })
} else {
  #if DEBUG
  fatalError("Can't hide behind snapshot while presenting other view controller")
  #endif
}

}

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