滚动旋转时 UICollectionView 崩溃（索引路径处补充项目的布局属性已更改但未失效..）

Question

关于如何解决滚动旋转时我的 UICollectionView 崩溃的任何想法？

我正在使用以下方法分别进行滚动和旋转，并且每种方法似乎都可以正常工作。我刚刚注意到同时做这两件事时我会遇到这个崩溃。因此，当我旋转设备并且在 prepareLayout 中计算新的布局属性时，这似乎与以下事实有关，持续滚动正在触发 "invalidateLayoutWithContext(invalidContext)"（见下文）。

想法？有没有办法在轮换期间放置任何滚动响应 on-hold （或忽略它们）？

旋转方法 在视图控制器的 viewWillLayoutSubviews 中，我使整个布局无效

self.cal.collectionViewLayout.invalidateLayout()

滚动方法 为了让我有一个 "sticky" 装饰视图 (header)，我不会使整个布局无效，因为它会降低性能，但请执行以下操作。在布局 class 中，我覆盖了 shouldInvalidateLayoutForBoundsChange

    override func shouldInvalidateLayoutForBoundsChange(newBounds: CGRect) -> Bool {
        let invalidContext : UICollectionViewLayoutInvalidationContext = self.invalidationContextForBoundsChange(newBounds)

        // Keep Header Sticky
invalidContext.invalidateDecorationElementsOfKind(GCCalendarLayoutKind_Decorative1, atIndexPaths: [headerDecorativeIndexPath])

        // Apply Invalidation
        self.invalidateLayoutWithContext(invalidContext)        

        // Return normal super return (just in case of future IOS upgrades)
        return super.shouldInvalidateLayoutForBoundsChange(newBounds)
    }

请注意，我在这里使装饰视图 (header) 无效，而崩溃的错误是关于我的补充视图布局不同。

错误

2015-10-30 07:14:30.181 test3_collectionview[17086:3102132] * Assertion failure in -[UICollectionViewData validateLayoutInRect:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3512.29.5/UICollectionViewData.m:408 2015-10-30 07:14:30.185 test3_collectionview[17086:3102132] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'layout attributes for supplementary item at index path ( {length = 2, path = 0 - 0}) changed from index path: ( {length = 2, path = 0 - 0}); element kind: (Decorative1); frame = (0 1085.5; 320 16); zIndex = 1; to index path: ( {length = 2, path = 0 - 0}); element kind: (Decorative1); frame = (0 853.5; 320 16); zIndex = 1; without invalidating the layout' *** First throw call stack:

Answer 1

我不确定这是否足够，但我会按照以下思路尝试一下（集合视图是滚动视图）：

import CoreGraphics

class myController: UIViewController, UIScrollViewDelegate {

    var myScrollView = UIScrollView()

    override func viewDidLoad() {
        self.view.addSubview(myScrollView)
    }

    // This will capture rotation events
    override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {
        self.myScrollView.scrollEnabled = false
        coordinator.notifyWhenInteractionEndsUsingBlock( {_ in self.myScrollView.scrollEnabled = true} )
        super.viewWillTransitionToSize(size, withTransitionCoordinator: coordinator)
    }

    func scrollViewDidScroll(scrollView: UIScrollView) {
        // This will not ignore scroll but perhaps can help keeping things "tidy" and "performant" during rotation.  Not sure
        if myScrollView.scrollEnabled == false {
            let offset = scrollView.contentOffset
            myScrollView.setContentOffset(offset, animated: false)
        }
    }   
}

滚动旋转时 UICollectionView 崩溃（索引路径处补充项目的布局属性已更改但未失效..）

UICollectionView crashing when scrolling whist rotating (layout attributes for supplementary item at index path changed without invalidating..)

ios

uicollectionview

uicollectionviewlayout