摘要

Question

摘要

我有一个内容UIViewController，它使用自定义转换呈现设置UIViewController。演示文稿位于presentViewController:animated:completion:。

当我稍后使用dismissViewControllerAnimated:completion:关闭设置时，演示控制器会突然跳回设置控制器演示之前的初始位置。

我在设备上有解决方法但不是模拟器。但是，我想知道我做错了什么，而不是黑客入侵让它消失的小屋。我还打算让这个动画互动，我怀疑这个问题会在我这样做时放大。

自定义转换 - 打开引擎盖

理想的效果是呈现控制器在屏幕上向下滑动，并且呈现的控制器被看作位于其后面，从它抬起以填满屏幕。在呈现控制器的使用寿命期间，呈现控制器的顶部保持在屏幕上。它停留在屏幕的底部，但高于显示的控制器。

您可以想象在汽车（前部控制器）上抬起引擎盖以查看后面的发动机（显示的设置），但是发动机罩在底部保持可见状态。

我计划对此进行改进，以便呈现控制器看起来真的以3d方式提升视角，但我还没有那么远。

当设置被取消时，原始显示控制器（发动机罩）应向上滑回屏幕，并且呈现的控制器（设置）稍微下沉（关闭发动机罩）。

代码

这里是切换屏幕上和屏幕外设置的方法（它只是由UIButton调用）。您会注意到呈现视图控制器将自己设置为<UIViewControllerTransitioningDelegate>。

-(void) toggleSettingsViewController
{
  const BOOL settingsAreShowing = [self presentedViewController] != nil;
  if(!settingsAreShowing)
  {
    UIViewController *const settingsController = [[self storyboard] instantiateViewControllerWithIdentifier: @"STSettingsViewController"];
    [settingsController setTransitioningDelegate: self];
    [settingsController setModalPresentationStyle: UIModalPresentationCustom];
    [self presentViewController: settingsController animated: YES completion: nil];
  }
  else
  {
    [self dismissViewControllerAnimated: YES completion: nil];
  }
}

要实现<UIViewControllerAnimatedTransitioning>，呈现视图控制器也会将其自身返回为<UIViewControllerAnimatedTransitioning>

-(id<UIViewControllerAnimatedTransitioning>) animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
  return self;
}

-(id<UIViewControllerAnimatedTransitioning>) animationControllerForDismissedController:(UIViewController *)dismissed
{
  // Test Point 1.
  return self;
}

最后，呈现视图控制器将收到animateTransition:：

-(void) animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
  UIViewController *const fromController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
  UIViewController *const toController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

  const BOOL isUnwinding = [toController presentedViewController] == fromController;
  const BOOL isPresenting = !isUnwinding;

  UIViewController * presentingController = isPresenting ? fromController : toController;
  UIViewController * presentedController = isPresenting ? toController : fromController;

  if(isPresenting)
  {
    // Add the presented controller (settings) to the view hierarchy _behind_ the presenting controller.
    [[transitionContext containerView] insertSubview: [presentedController view] belowSubview: [presentingController view]];

    // Set up the initial position of the presented settings controller. Scale it down so it seems in the distance. Alpha it down so it is dark and shadowed.
    presentedController.view.transform = CGAffineTransformMakeScale(0.9, 0.9);
    presentedController.view.alpha = 0.7;

    [UIView animateWithDuration: [self transitionDuration: transitionContext] animations:^{
      // Lift up the presented controller.
      presentedController.view.transform = CGAffineTransformMakeScale(1.0, 1.0);

      // Brighten the presented controller (out of shadow).
      presentedController.view.alpha = 1;

      // Push the presenting controller down the screen – 3d effect to be added later.
      presentingController.view.layer.transform = CATransform3DMakeTranslation(0,400,0);
     } completion: ^(BOOL finished){
       [transitionContext completeTransition: ![transitionContext transitionWasCancelled]];
     }];
  }
  else
  {
    // Test Point 2.

    // !!!This line should not be needed!!!
    // It resets the presenting controller to where it ought to be anyway.
    presentingController.view.layer.transform = CATransform3DMakeTranslation(0,400,0);

    [UIView animateWithDuration: [self transitionDuration: transitionContext] animations:^{
      // Bring the presenting controller back to its original position.
      presentingController.view.layer.transform = CATransform3DIdentity;

      // Lower the presented controller again and put it back in to shade.
      presentedController.view.transform = CGAffineTransformMakeScale(0.9, 0.9);
      presentedController.view.alpha = 0.4;
    } completion:^(BOOL finished) {
      [transitionContext completeTransition: ![transitionContext transitionWasCancelled]];
    }];
  }
}

-(NSTimeInterval) transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
  return 0.5;
}

问题

在上面的代码中，我已经指出 !!!不应该需要此行!!! 。

在测试点1 和测试点2 之间发生的情况是，呈现视图控制器的屏幕位置被重置为默认的全屏界限。因此，它不是在屏幕的底部准备好再次平滑地重新启动动画，而是突然跳到屏幕上以确定它是否也能平滑地制作动画！

我尝试了各种方法在屏幕上动画显示视图控制器：

我改变了观点的框架。
我改变了观点的转变。
我已经改变了它的视图层的3D变换。

在所有情况下，在测试点1 ，当要求转换委托时，呈现控制器按照我的预期设置。但是，在所有情况下，在测试点2 时，呈现视图控制器已丢失正确的位置并已被清除＆＃34;拥有我想要动画的正常全屏位置。

在上面的工作中，我明确地将呈现视图控制器重新定位到动画开始处的位置 !!!不应该需要这一行!!! 。这似乎适用于具有当前版本iOS 7的设备。但是，在模拟器上，控制器在清除位置可见至少一帧。

我怀疑我做错了什么，而且我会在解决另一个问题时遇到麻烦。

任何想法是怎么回事？谢谢！

Answer 1

使用自定义过渡动画解雇模态呈现的视图控制器的一些潜在问题：

将显示的（＆＃34;到＆＃34;）视图添加到容器中，然后将显示的视图放在前面。不要添加展示视图，因为您可能会将其从当前的超级视图中删除。
在关闭时，UIKit会在调用animateTransition之前将呈现视图的alpha设置为0 。因此，您希望在解雇您的解雇动画之前将其设置为1.0或完成当前时的任何内容。

同样适用于所呈现的视图转换。在关闭时，它会在调用animateTransition之前重置为identity。

鉴于这一切，我认为这应该有效：

-(void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext { UIViewController *fromController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey]; UIViewController *toController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey]; UIView *containerView = transitionContext.containerView; const BOOL isUnwinding = [toController presentedViewController] == fromController; const BOOL isPresenting = !isUnwinding; UIViewController *presentingController = isPresenting ? fromController : toController; UIViewController *presentedController = isPresenting ? toController : fromController; [containerView addSubview:presentingController.view]; [containerView bringSubviewToFront:presentingController.view]; if(isPresenting) { // Set up the initial position of the presented settings controller. Scale it down so it seems in the distance. Alpha it down so it is dark and shadowed. presentedController.view.transform = CGAffineTransformMakeScale(0.9, 0.9); presentedController.view.alpha = 0.7; [UIView animateWithDuration: [self transitionDuration: transitionContext] animations:^{ // Lift up the presented controller. presentedController.view.transform = CGAffineTransformMakeScale(1.0, 1.0); // Brighten the presented controller (out of shadow). presentedController.view.alpha = 1; // Push the presenting controller down the screen – 3d effect to be added later. presentingController.view.layer.transform = CATransform3DMakeTranslation(0,400,0); } completion: ^(BOOL finished){ [transitionContext completeTransition: ![transitionContext transitionWasCancelled]]; }]; } else { presentedController.view.transform = CGAffineTransformMakeScale(0.9, 0.9); presentedController.view.alpha = 0.7; [UIView animateWithDuration: [self transitionDuration: transitionContext] animations:^{ // Bring the presenting controller back to its original position. presentingController.view.layer.transform = CATransform3DIdentity; // Lower the presented controller again and put it back in to shade. presentedController.view.transform = CGAffineTransformMakeScale(0.9, 0.9); presentedController.view.alpha = 0.4; } completion:^(BOOL finished) { [transitionContext completeTransition: ![transitionContext transitionWasCancelled]]; }]; } }

Answer 2

最初，我考虑在CATransition和presentViewController:animated:completion:视图控制器时使用dismissViewControllerAnimated:completion:来获得自定义转换效果。但是，当您显示设置视图控制器时，您希望显示View Controller的一部分，然后我认为CATransition无效，因为您无法完全控制您想要移动视图控制器的距离。

我认为最简单的方法是使用一个带有两个全屏UIView的View Controller。对于第一个UIView（View Controller的视图，即self.view），您可以布局设置，而在第二个UIView上，它是常规视图。在ViewDidLoad中，使用[self.view addSubview:2ndView];添加第二个视图。稍后当您想要显示设置视图时，可以执行

CGRect frame = secondView.frame;
frame.origin.y = the_y_coordinate_you_like;
UIView animateWithDuration:0.2 animations:^{
    secondView.frame = frame;
}];

然后用另一种方式将第二视图带回来。

UIViewController - 自定义解除转换的问题

摘要

自定义转换 - 打开引擎盖

代码

问题

2 个答案: