Drag and Drop from NSTableView fails if more items are written than rows dragged

Originator:Daniel.Alexander.Alm
Number:rdar://44135683 Date Originated:09/05/2018
Status:Open Resolved:
Product:macOS + SDK | AppKit Product Version:macOS 10.14 Mojave beta 18A384a
Classification:Crash Reproducible:Always
 
Summary:
When writing more pasteboard items to the pasteboard than rows have been dragged in an NSTableView/NSOutlineView/NSCollectionView/NSBrowser, the app crashes.

This has also been described in https://forums.developer.apple.com/thread/107824.

Steps to Reproduce:
1. Implement `func tableView(_ tableView: NSTableView, writeRowsWith rowIndexes: IndexSet, to pboard: NSPasteboard) -> Bool` to write more pasteboard items than rows selected.
2. Drag a row in the table view.

Attached is a sample project where dragging the "foo" element in the table instantly triggers a crash.

Expected Results:
All items are written to the dragging pasteboard and made available to receivers of the drop. Note that there are legitimate reasons for attaching more than one pasteboard item to a row, e.g. when the row represents a set of multiple files.


Actual Results:
The app crashes with the following error and stack trace:
2018-09-05 14:09:57.175241+0200 TableViewPasteboardCrash[3106:66642] [General] There are 2 items on the pasteboard, but 1 drag images. There must be 1 draggingItem per pasteboardItem.
2018-09-05 14:09:57.176486+0200 TableViewPasteboardCrash[3106:66642] [General] (
	0   CoreFoundation                      0x00007fff4c1dd43d __exceptionPreprocess + 256
	1   libobjc.A.dylib                     0x00007fff7802b720 objc_exception_throw + 48
	2   CoreFoundation                      0x00007fff4c1dd26f +[NSException raise:format:] + 201
	3   AppKit                              0x00007fff49a03387 -[NSDraggingSession(NSInternal) _initWithPasteboard:image:offset:source:] + 247
	4   AppKit                              0x00007fff49a02d9f -[NSCoreDragManager dragImage:fromWindow:at:offset:event:pasteboard:source:slideBack:] + 1919
	5   AppKit                              0x00007fff49a02611 -[NSWindow(NSDrag) dragImage:at:offset:event:pasteboard:source:slideBack:] + 134
	6   AppKit                              0x00007fff49eb9a75 -[NSTableView _doImageDragUsingRowsWithIndexes:event:pasteboard:source:slideBack:startRow:] + 656
	7   AppKit                              0x00007fff49eb9f09 -[NSTableView __doImageDragUsingRowsWithIndexes:event:pasteboard:source:slideBack:startRow:] + 276
	8   AppKit                              0x00007fff49ebac9e -[NSTableView _performClassicDragOfIndexes:hitRow:event:] + 466
	9   AppKit                              0x00007fff49a31cf8 -[NSTableView _performDragFromMouseDown:] + 474
	10  AppKit                              0x00007fff49a2fffc -[NSTableView mouseDown:] + 798
	11  AppKit                              0x00007fff498b46ef -[NSWindow(NSEventRouting) _handleMouseDownEvent:isDelayedEvent:] + 5668
	12  AppKit                              0x00007fff497e872f -[NSWindow(NSEventRouting) _reallySendEvent:isDelayedEvent:] + 2319
	13  AppKit                              0x00007fff497e7bd5 -[NSWindow(NSEventRouting) sendEvent:] + 481
)


Version/Build: macOS 10.14 Mojave beta 18A384a

Comments

The same problem was discovered in an NSTokenFIeld

The same problem was discovered in an NSTokenFIeld.

< NSTokenAttachmentCell: 0x60000217f840 >: There was an exception (There are 3 items on the pasteboard, but 1 drag images. There must be 1 draggingItem per pasteboardItem.) raised while processing drag. Ignoring...

By absterno at Oct. 1, 2018, 9:24 p.m. (reply...)

Please note: Reports posted here will not necessarily be seen by Apple. All problems should be submitted at bugreport.apple.com before they are posted here. Please only post information for Radars that you have filed yourself, and please do not include Apple confidential information in your posts. Thank you!