UIPageViewController转换'非平衡调用开始/结束外观转换为'

当我通过UIPageViewController比它的转换animation更快地导航时，我得到了“ Unbalanced calls to begin/end appearance transitions for <MyDataViewController>的Unbalanced calls to begin/end appearance transitions for <MyDataViewController> ”，并且直到我尝试翻页为止， Unbalanced calls to begin/end appearance transitions for <MyDataViewController>中的两个视图之一才显示出来。

任何人有解决这个错误的想法？

Answer 1

上面的答案是对的，但是我认为比所需要的更详细，而且食谱是有帮助的。 所以这里似乎是为我工作：

在设置和调用pageViewController的视图控制器中，声明：

 @property (assign) BOOL pageIsAnimating; 

并在viewDidLoad：

  pageIsAnimating = NO; 

添加这个：

 - (void)pageViewController:(UIPageViewController *)pageViewController willTransitionToViewControllers:(NSArray *)pendingViewControllers { pageIsAnimating = YES; } 

并添加几行：

 - (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed { if (completed || finished) // Turn is either finished or aborted pageIsAnimating = NO; ... } 

通过拒绝提供视图控制器信息来抑制手势：

 - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController { if (pageIsAnimating) return nil; ... return after; } - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController { if (pageIsAnimating) return nil; ... return before; } 

哦，方向改变重置标志：

 - (UIPageViewControllerSpineLocation)pageViewController:(UIPageViewController *)pageViewController spineLocationForInterfaceOrientation:(UIInterfaceOrientation)orientation { pageIsAnimating = NO; ... } 

Answer 2

解决以下步骤：
1-声明一个标志来表示animation已经完成或没有完成：

 BOOL pageAnimationFinished; 

2-在viewDidLoad中将此标志设置为true：

 pageAnimationFinished = YES; 

3-为pageViewController禁用tapGesture并将“self”分配给panGestureRecognizer委托：

 for (UIGestureRecognizer * gesRecog in self.pageViewController.gestureRecognizers) { if ([gesRecog isKindOfClass:[UITapGestureRecognizer class]]) gesRecog.enabled = NO; else if ([gesRecog isKindOfClass:[UIPanGestureRecognizer class]]) gesRecog.delegate = self; } 

4-通过以下手势识别器委托方法允许/禁止panGestureRecognizer：

 -(BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer { if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]] && ([gestureRecognizer.view isEqual:self.view] || [gestureRecognizer.view isEqual:self.pageViewController.view])) { UIPanGestureRecognizer * panGes = (UIPanGestureRecognizer *)gestureRecognizer; if(!pageAnimationFinished || (currentPage < minimumPage && [panGes velocityInView:self.view].x < 0) || (currentPage > maximumPage && [panGes velocityInView:self.view].x > 0)) return NO; pageAnimationFinished = NO; } return YES; } 

5-添加下面的pageViewController委托方法：

 - (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed { pageAnimationFinished = YES; } 

Answer 3

来自Basem Saadawy的良好回答 ，但它有一些缺陷。

其实代表的gestureRecognizerShouldBegin：可以被调用，没有进一步的animation开始。 如果通过垂直手指的移动开始手势，并且水平偏移不足以启动animation（但足以启动gestureRecognizerShouldBegin：），则可以这样做 。 因此，我们的variablespageAnimationFinished将被设置为NO没有实际的animation。 因此， pageViewController：didFinishAnimating：将永远不会被调用，并且您将冻结当前页面而无法更改它。

这就是为什么把NO赋给这个variables的一个更好的地方是一个手势识别器的动作方法，检查它的速度和转换（我们只对水平方向感兴趣）。

所以最后的步骤是：

1）声明一个实例variables（一个标志）：

 BOOL pageAnimationFinished; 

2）设置其初始值

 - (void)viewDidLoad { [super viewDidLoad]; ... pageAnimationFinished = YES; } 

3）为平移手势识别器分配委托和自定义操作

 for (UIGestureRecognizer * gesRecog in self.pageViewController.gestureRecognizers) { if ([gesRecog isKindOfClass:[UIPanGestureRecognizer class]]) { gesRecog.delegate = self; [gr addTarget:self action:@selector(handlePan:)]; } } 

3'）当手势的平移水平方向较大，手指水平移动时，真正开始animation。
我猜在UIPageViewController分配的内部识别器的动作中使用了相同的逻辑。

 - (void) handlePan:(UIPanGestureRecognizer *)gestureRecognizer { if (pageAnimationFinished && gestureRecognizer.state == UIGestureRecognizerStateChanged) { CGPoint vel = [gestureRecognizer velocityInView:self.view]; CGPoint tr = [gestureRecognizer translationInView:self.view]; if (ABS(vel.x) > ABS(vel.y) && ABS(tr.x) > ABS(tr.y)) pageAnimationFinished = NO; // correct place } } 

4）如果animation未完成，则禁止手势。

 -(BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer { if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]] && ([gestureRecognizer.view isEqual:self.view] || [gestureRecognizer.view isEqual:self.pageViewController.view])) { UIPanGestureRecognizer * panGes = (UIPanGestureRecognizer *)gestureRecognizer; if(!pageAnimationFinished || (currentPage < minimumPage && [panGes velocityInView:self.view].x < 0) || (currentPage > maximumPage && [panGes velocityInView:self.view].x > 0)) return NO; } return YES; } 

5）animation完成

 - (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed { pageAnimationFinished = YES; } 

我玩得太多了，似乎这是一个很好的解决scheme，效果很好。

Answer 4

以下是使用委托的QUICK版本：

添加这段代码（确保你的头文件或类扩展中包含了UIPageViewControllerDelegate，并赋值self.pageViewController.delegate = self; ）：

 - (void)pageViewController:(UIPageViewController *)pageViewController willTransitionToViewControllers:(NSArray *)pendingViewControllers { self.pageAnimationFinished = NO; } - (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed { self.pageAnimationFinished = YES; } 

然后检查self.pageAnimationFinished并返回nil，如果它是== NO 。

较长的说明：

 - (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed 

我们可以使用UIPageViewControllerDelegate这个委托方法来知道从页面翻转或者滑动完成的animation何时完成。 使用这个我们可以像这样实现它：

 - (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed { pageAnimationFinished = YES; } 

那么，只需返回nil

 - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(PageViewController *)viewController 

和

 - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(PageViewController *)viewController 

什么时候

pageAnimationFinished == NO 。 animation时一定要将pageAnimationFinished设置为NO 。 知道何时使用animation的最好方法是使用相反的方法

 - (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed 

即：

 - (void)pageViewController:(UIPageViewController *)pageViewController willTransitionToViewControllers:(NSArray *)pendingViewControllers 

从那以后，我一直没有看到这种警告，这可以用其他解决scheme的三分之一来完成。 而且更容易遵循。

Answer 5

Bill Cheswick的答案的Swift版本（现在是最高的答案）：

添加一个variables来保持当前状态：

 var pageIsAnimating = false 

设置animation状态：

 func pageViewController(pageViewController: UIPageViewController, willTransitionToViewControllers pendingViewControllers: [UIViewController]) { self.pageIsAnimating = true } func pageViewController(pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) { if finished || completed { self.pageIsAnimating = false } } 

如果目前正在进行animation制作，则阻止转场：

 func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? { if self.pageIsAnimating { return nil } // Your code here } func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? { if self.pageIsAnimating { return nil } // Your code here } 

谢谢Bill Cheswick！

Answer 6

我的解决scheme迅速，简单，有效：

1. 将pageviewcontroller委托设置为您的类

2. 添加下面的代码

    extension MyPageVC: UIPageViewControllerDelegate { func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) { self.view.isUserInteractionEnabled = false } func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) { self.view.isUserInteractionEnabled = true } } 

Answer 7

这个怎么样：

 - (void)pageViewController:(UIPageViewController*)pgVC willTransitionToViewControllers:(NSArray*)pendingVCs { pgVC.dataSource = nil; // ... to disallow user to change pages until animation completes } - (void)pageViewController:(UIPageViewController*)pgVC didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray*)prevVCs transitionCompleted:(BOOL)completed { if(completed || finished) { pgVC.dataSource = _pgViewDataSource; // ... to allow user to change pages again } } 

Answer 8

利用你的UIPageViewControllerDelegate方法并设置警戒，防止在检测到过多的页面转动时创build新的页面视图。

1. 您可以禁用手势识别器
2. 将“userInteraction”设置为在UIView上禁用
3. 在UIPageViewController上维护一个标志，以便在出现animation时忽略进一步的input。 （关于这个选项的警告.. ios5和ios6有不同的方式来确定何时animation开始..）

Answer 9

我不得不把它添加到viewDidAppear：使其工作

  - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; self.pageAnimationFinished = YES; } 

Answer 10

我将尝试在转换时忽略UIPageViewControllers上的手势。