UICollectionView交互式转换抛出异常

我试图在UICollectionView上实现双指展开，并遇到一些麻烦。与我可以找到的所有示例代码不同，我没有将它作为交互式UINavigationController转换的一部分 - 我只需要就地扩展项目。UICollectionView交互式转换抛出异常

这里是我的捏手势识别：

- (void)pinchGestureDidPinch:(UIPinchGestureRecognizer *)recognizer 
{ 
    CGFloat targetScale = 3.0; 
    CGFloat scale = recognizer.scale; 
    if (recognizer.state == UIGestureRecognizerStateBegan) { 
     CGPoint point = [recognizer locationInView:self.collectionView]; 
     NSIndexPath *rowUnder = [self.collectionView indexPathForItemAtPoint:point]; 
     self.pinchingRow = [NSIndexPath indexPathForItem:0 inSection:rowUnder.section]; 
     self.currentState = HACStreamViewControllerTransitioning; 
     self.expandedLayout.expandedSection = self.pinchingRow.section; 
     self.transitionLayout = [self.collectionView startInteractiveTransitionToCollectionViewLayout:self.expandedLayout completion:nil]; 
    } else if (recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled) { 
     if (scale >= targetScale) { 
      [self.collectionView finishInteractiveTransition]; 
      self.currentState = HACStreamViewControllerExpanded; 
     } else { 
      [self.collectionView cancelInteractiveTransition]; 
      self.currentState = HACStreamViewControllerCollapsed; 
     } 
    } else { 
     // change 
     CGFloat progress = MIN(targetScale/scale, 1.0); 
     progress = MAX(0.0, progress); 
     self.transitionLayout.transitionProgress = progress; 
     [self.transitionLayout invalidateLayout]; 
    } 
}

调用startInteractiveTransitionToCollectionViewLayout：导致异常，但：

0 ???         0x0fcf577f 0x0 + 265246591, 
1 UIKit        0x01e1f582 -[UICollectionViewTransitionLayout setTransitionProgress:] + 643, 
2 UIKit        0x01d13053 -[UICollectionView _setCollectionViewLayout:animated:isInteractive:completion:] + 658, 
3 UIKit        0x01d12be8 -[UICollectionView setCollectionViewLayout:] + 225, 
4 UIKit        0x01d15e0a -[UICollectionView startInteractiveTransitionToCollectionViewLayout:completion:] + 821, 
5 HAW Couples       0x0001beae -[HACStreamViewController pinchGestureDidPinch:] + 782, 
6 UIKit        0x01a74f8c _UIGestureRecognizerSendActions + 230, 
7 UIKit        0x01a73c00 -[UIGestureRecognizer _updateGestureWithEvent:buttonEvent:] + 383, 
8 UIKit        0x01a7566d -[UIGestureRecognizer _delayedUpdateGesture] + 60, 
9 UIKit        0x01a78bcd ___UIGestureRecognizerUpdate_block_invoke + 57, 
10 UIKit        0x01a78b4e _UIGestureRecognizerRemoveObjectsFromArrayAndApplyBlocks + 317, 
11 UIKit        0x01a6f248 _UIGestureRecognizerUpdate + 199, 
12 UIKit        0x0173bd4a -[UIWindow _sendGesturesForEvent:] + 1291, 
13 UIKit        0x0173cc6a -[UIWindow sendEvent:] + 1030, 
14 UIKit        0x01710a36 -[UIApplication sendEvent:] + 242, 
15 UIKit        0x016fad9f _UIApplicationHandleEventQueue + 11421, 
16 CoreFoundation      0x033988af __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15, 
17 CoreFoundation      0x0339823b __CFRunLoopDoSources0 + 235, 
18 CoreFoundation      0x033b530e __CFRunLoopRun + 910, 
19 CoreFoundation      0x033b4b33 CFRunLoopRunSpecific + 467, 
20 CoreFoundation      0x033b494b CFRunLoopRunInMode + 123, 
21 GraphicsServices     0x042619d7 GSEventRunModal + 192, 
22 GraphicsServices     0x042617fe GSEventRun + 104, 
23 UIKit        0x016fd94b UIApplicationMain + 1225, 
24 HAW Couples       0x0000eefd main + 141, 
25 libdyld.dylib      0x03bd5725 start + 0

异常的消息：

*** setObjectForKey: object cannot be nil (key: actualAttribute)

我验证过我的“目标”UICollectionViewLayout是很好的。以下替代（用自来水触发）正常工作，并且动画预期：

[self.collectionView setCollectionViewLayout:self.expandedLayout animated:YES completion:^(BOOL finished) { 
}];

来源

2013-10-16 Jerry Wong

我有完全同样的问题，在我的情况下，在布局中的一个自定义布局，另一个出现这种崩溃是UICollectionViewFlowLayout。我仍在研究这个问题，但我想知道你是否有相同的设置。

编辑1）在我的自定义布局中，我有装饰视图，并且我在[UICollectionViewLayout layoutAttributesForElementsInRect：]操作中为装饰视图返回了UICollectionViewLayoutAttributes。我在删除装饰视图的布局属性后进行测试，现在它完美地工作。在一个布局中查看其他布局中不存在的布局似乎是个问题，当我找出更多信息时，我会更新我的答案。

来源

2013-11-09 16:26:43 JYC

是的，我有同样的问题，这是从不正确的装饰视图跟踪。 – Kelan

UICollectionView交互式转换抛出异常

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