swift – 崩溃：[NSCollectionViewData layoutAttributesForItemAtIndexPath]

现在试着了解这次崩溃.

对于某些用户(随机,操作系统10.14 / 10.14.1),应用程序在第一次加载时崩溃.

Crashed: com.apple.main-thread
EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x0000000000000000
-[NSCollectionViewData layoutAttributesForItemAtIndexPath:]

Crashed: com.apple.main-thread
0  UIFoundation                   0x7fff7ac71c6a -[NSCollectionViewData layoutAttributesForItemAtIndexPath:] + 72
1  UIFoundation                   0x7fff7ac3cb52 -[_NSCollectionViewCore _updateVisibleCellsNow:] + 7748
2  UIFoundation                   0x7fff7ac358a9 -[_NSCollectionViewCore _layoutItems] + 298
3  AppKit                         0x7fff5019dbc2 -[NSCollectionView layout] + 360
4  AppKit                         0x7fff5002e755 _NSViewLayout + 587
5  AppKit                         0x7fff5002e0fc -[NSView _layoutSubtreeWithOldSize:] + 446
6  AppKit                         0x7fff5002e375 -[NSView _layoutSubtreeWithOldSize:] + 1079
7  AppKit                         0x7fff5002e375 -[NSView _layoutSubtreeWithOldSize:] + 1079
8  AppKit                         0x7fff5002e375 -[NSView _layoutSubtreeWithOldSize:] + 1079
9  AppKit                         0x7fff5002e375 -[NSView _layoutSubtreeWithOldSize:] + 1079
10 AppKit                         0x7fff5002e375 -[NSView _layoutSubtreeWithOldSize:] + 1079
11 AppKit                         0x7fff5002e375 -[NSView _layoutSubtreeWithOldSize:] + 1079
12 AppKit                         0x7fff5002e375 -[NSView _layoutSubtreeWithOldSize:] + 1079
13 AppKit                         0x7fff5002bb96 -[NSView _layoutSubtreeIfNeededAndAllowTemporaryEngine:] + 1358
14 AppKit                         0x7fff5002b332 -[NSWindow(NSConstraintBasedLayout) _layoutViewTree] + 148
15 AppKit                         0x7fff5003cfee -[NSWindow(NSConstraintBasedLayout) layoutIfNeeded] + 263
16 AppKit                         0x7fff50041469 -[NSWindow displayIfNeeded] + 180
17 AppKit                         0x7fff5004130f __NSWindowGetdisplayCycleObserverFordisplay_block_invoke + 722
18 AppKit                         0x7fff5003c41a NSdisplayCycleObserverInvoke + 170
19 AppKit                         0x7fff5003bf8f NSdisplayCycleFlush + 1073
20 QuartzCore                     0x7fff5d9621d3 CA::Transaction::run_commit_handlers(CATransactionPhase) + 49
21 QuartzCore                     0x7fff5d961b9a CA::Transaction::commit() + 186
22 AppKit                         0x7fff5003b8f5 __65+[CATransaction(NSCATransaction) NS_setFlushesWithdisplayRefresh]_block_invoke + 274
23 CoreFoundation                 0x7fff52a3f95d __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
24 CoreFoundation                 0x7fff52a3f892 __CFRunLoopDoObservers + 452
25 CoreFoundation                 0x7fff529e13c5 __CFRunLoopRun + 1166
26 CoreFoundation                 0x7fff529e0ce4 CFRunLoopRunSpecific + 463
27 HIToolBox                      0x7fff51c7a895 runcurrentEventLoopInMode + 293
28 HIToolBox                      0x7fff51c7a5cb ReceiveNextEventCommon + 618
29 HIToolBox                      0x7fff51c7a348 _BlockUntilNextEventMatchingListInModeWithFilter + 64
30 AppKit                         0x7fff4ff3795b _DPSNextEvent + 997
31 AppKit                         0x7fff4ff366fa -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 1362
32 AppKit                         0x7fff4ff3075d -[NSApplication run] + 699
33 AppKit                         0x7fff4ff1fe97 NSApplicationMain + 780
34 TodoDock                       0x105173a99 main (AppDelegate.swift:18)
35 libdyld.dylib                  0x7fff7fa7a085 start + 1

从它的外观来看,似乎应用程序还没有事件加载.

我甚至设法找到一个有同样问题的人,在他的机器上安装Xcode并在本地运行相同版本,一切正常！
不仅如此,我做了之后,下载的应用程序也工作了！这太奇怪了,我真的不知道发生了什么.
更多的用户正在宣传这一点,但不是全部.

解决方法

我在开始时遇到了同样的随机崩溃问题.

可能的原因：

> CollectionViewItem具有不同的大小
>视图加载前调用的viewFor()(切换或更改或编辑视图时发生)
>编辑影响其他集合视图项的一个集合视图项的大小(如果删除前者,则可能)

我通过添加if条件来修复它,以检查集合视图是否为零.还可以通过在更改视图时检查数据源numberOfItems是否一致.