Swift 2: UITableView 'reloadSections' method crash in iOS 9 - ios

Question

My app was working fine prior to the forced upgrade to Swift 2.x. My code below is executed on an IBAction for a button that "collapses" the cell, e.g. it replaces it with another layout and then attempts to reload the cell, which for various reasons I've been forced to include each cell in its own section (so, extensibly I'm reloading the section). I've tried outputting various variables to the terminal; the inputs are sound. I've also tried wrapping this in .beginUpdates() and .endUpdates() and when walking through this in the debugger, it will just throw the below exception on the .endUpdates() call instead of the .reloadSections() call. I have also tried replacing .reloadSections() with a blanket call to .reloadData() and I receive the same stack trace, making me believe it's internal to the TableView object somehow.
// Set Selected Patient Configuration to "Collapsed"
patientList.patients[ sender.tag ].updateConfiguration( collapsedConfiguration )
let animation = UITableViewRowAnimation.Automatic
// Retrieve Current Table View and Animate Changes
let tableView = self.superview!.superview as! UITableView
// Reload Section with Animation
tableView.reloadSections(NSIndexSet( index: sender.tag ), withRowAnimation: animation )
My code will evaluate the backing data's collapsed state and draw it in either the full or collapsed view.
*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM insertObject:atIndex:]: index 2 beyond bounds [0 .. 0]'
*** First throw call stack:
(
0 CoreFoundation 0x00e2fa84 __exceptionPreprocess + 180
1 libobjc.A.dylib 0x03235e02 objc_exception_throw + 50
2 CoreFoundation 0x00cdd211 -[__NSArrayM insertObject:atIndex:] + 881
3 Foundation 0x01510134 -[NSKeyValueSlowMutableArray insertObject:atIndex:] + 115
4 CoreFoundation 0x00d38630 -[NSMutableArray insertObjects:count:atIndex:] + 192
5 CoreFoundation 0x00d38322 -[NSMutableArray insertObjectsFromArray:range:atIndex:] + 322
6 CoreFoundation 0x00d381c2 -[NSMutableArray addObjectsFromArray:] + 834
7 UIKit 0x024f4d4f -[UIRuntimeOutletCollectionConnection performConnect] + 964
8 UIKit 0x024f4daf -[UIRuntimeOutletCollectionConnection connect] + 33
9 libobjc.A.dylib 0x0324a00c -[NSObject performSelector:] + 62
10 CoreFoundation 0x00d60571 -[NSArray makeObjectsPerformSelector:] + 273
11 UIKit 0x021b06f6 -[UINib instantiateWithOwner:options:] + 2102
12 UIKit 0x01eeed6c -[UITableView _dequeueReusableViewOfType:withIdentifier:] + 457
13 UIKit 0x01eef173 -[UITableView dequeueReusableCellWithIdentifier:] + 48
14 Halo 0x001b5174 _TFC4Halo18MainViewController9tableViewfS0_FTCSo11UITableView21cellForRowAtIndexPathCSo11NSIndexPath_CSo15UITableViewCell + 2356
15 Halo 0x001be459 _TToFC4Halo18MainViewController9tableViewfS0_FTCSo11UITableView21cellForRowAtIndexPathCSo11NSIndexPath_CSo15UITableViewCell + 89
16 UIKit 0x01f03a19 -[UITableView _createPreparedCellForGlobalRow:withIndexPath:willDisplay:] + 782
17 UIKit 0x01f03b47 -[UITableView _createPreparedCellForGlobalRow:willDisplay:] + 90
18 UIKit 0x022568cc -[_UITableViewUpdateSupport(Private) _setupAnimationsForNewlyInsertedCells] + 8353
19 UIKit 0x0226181a -[_UITableViewUpdateSupport _setupAnimations] + 161
20 UIKit 0x01ed7fd3 -[UITableView _updateWithItems:updateSupport:] + 3653
21 UIKit 0x01ecfc91 -[UITableView _endCellAnimationsWithContext:] + 17491
22 UIKit 0x01eea538 -[UITableView _updateSections:updateAction:withRowAnimation:headerFooterOnly:] + 460
23 UIKit 0x01eea625 -[UITableView reloadSections:withRowAnimation:] + 73
24 Halo 0x00105e10 _TFC4Halo28FullPatientViewTableViewCell19collapseButtonPressfS0_FCSo8UIButtonT_ + 6208
25 Halo 0x0010645d _TToFC4Halo28FullPatientViewTableViewCell19collapseButtonPressfS0_FCSo8UIButtonT_ + 61
26 libobjc.A.dylib 0x0324a0b5 -[NSObject performSelector:withObject:withObject:] + 84
27 UIKit 0x01d8016a -[UIApplication sendAction:to:from:forEvent:] + 118
28 UIKit 0x01d800e9 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 64
29 UIKit 0x01f1e19f -[UIControl sendAction:to:forEvent:] + 79
30 UIKit 0x01f1e51f -[UIControl _sendActionsForEvents:withEvent:] + 408
31 UIKit 0x01f1d525 -[UIControl touchesEnded:withEvent:] + 714
32 UIKit 0x022efeaa _UIGestureRecognizerUpdate + 12763
33 UIKit 0x01dfabdf -[UIWindow _sendGesturesForEvent:] + 1559
34 UIKit 0x01dfc298 -[UIWindow sendEvent:] + 1137
35 UIKit 0x01da1efb -[UIApplication sendEvent:] + 266
36 UIKit 0x01d77cb6 _UIApplicationHandleEventQueue + 7802
37 CoreFoundation 0x00d49d1f __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
38 CoreFoundation 0x00d3f9ab __CFRunLoopDoSources0 + 523
39 CoreFoundation 0x00d3edc8 __CFRunLoopRun + 1032
40 CoreFoundation 0x00d3e706 CFRunLoopRunSpecific + 470
41 CoreFoundation 0x00d3e51b CFRunLoopRunInMode + 123
42 GraphicsServices 0x058c0664 GSEventRunModal + 192
43 GraphicsServices 0x058c04a1 GSEventRun + 104
44 UIKit 0x01d7e1eb UIApplicationMain + 160
45 Halo 0x0011eb6c main + 140
46 libdyld.dylib 0x03ceca21 start + 1
47 ??? 0x00000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
The stack is not very helpful to me and I can't even figure out the opening message: "insertObject:atIndex:]: index 2 beyond bounds [0 .. 0]." No where in this sample and my test with a single table entry should there be an index of '2.' Any help you could provide would be appreciated.
Here's my 'bt' on this exception:
* thread #1: tid = 0xc9ca7, 0x0401969a libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
frame #0: 0x0401969a libsystem_kernel.dylib`__pthread_kill + 10
frame #1: 0x03fe4634 libsystem_pthread.dylib`pthread_kill + 101
frame #2: 0x03d9339d libsystem_c.dylib`abort + 156
frame #3: 0x04034ae7 libc++abi.dylib`abort_message + 151
frame #4: 0x04055683 libc++abi.dylib`default_terminate_handler() + 300
frame #5: 0x032360b6 libobjc.A.dylib`_objc_terminate() + 108
frame #6: 0x04052d0d libc++abi.dylib`std::__terminate(void (*)()) + 14
frame #7: 0x0405293e libc++abi.dylib`__cxa_rethrow + 103
frame #8: 0x03235fad libobjc.A.dylib`objc_exception_rethrow + 47
frame #9: 0x00d3e7d0 CoreFoundation`CFRunLoopRunSpecific + 672
frame #10: 0x00d3e51b CoreFoundation`CFRunLoopRunInMode + 123
frame #11: 0x058c0664 GraphicsServices`GSEventRunModal + 192
frame #12: 0x058c04a1 GraphicsServices`GSEventRun + 104
frame #13: 0x01d7e1eb UIKit`UIApplicationMain + 160
* frame #14: 0x0011eb6c Halo`main + 140 at AppDelegate.swift:26
frame #15: 0x03ceca21 libdyld.dylib`start + 1
Per request, here's the code followed by the output:
// Retrieve Current Table View and Animate Changes
let tableView = self.superview!.superview as! UITableView
// Test Output
print( "tableView.numberOfSections: \(tableView.numberOfSections)" )
print( "tableView.numberOfRowsInSection( sender.tag ): \(tableView.numberOfRowsInSection( sender.tag ))" )
// Reload Section with Animation
tableView.reloadSections(NSIndexSet( index: sender.tag ), withRowAnimation: animation )
tableView.numberOfSections: 1
tableView.numberOfRowsInSection( sender.tag ): 1

Answer 1

This section of the stack trace (probably) means that you have an IBOutletCollection, and UIKit is now trying to populate it from a storyboard or nib:
7 UIKit 0x024f4d4f -[UIRuntimeOutletCollectionConnection performConnect] + 964
8 UIKit 0x024f4daf -[UIRuntimeOutletCollectionConnection connect] + 33
And this section looks like it’s trying to add bound objects to an existing array:
2 CoreFoundation 0x00cdd211 -[__NSArrayM insertObject:atIndex:] + 881
3 Foundation 0x01510134 -[NSKeyValueSlowMutableArray insertObject:atIndex:] + 115
4 CoreFoundation 0x00d38630 -[NSMutableArray insertObjects:count:atIndex:] + 192
5 CoreFoundation 0x00d38322 -[NSMutableArray insertObjectsFromArray:range:atIndex:] + 322
6 CoreFoundation 0x00d381c2 -[NSMutableArray addObjectsFromArray:] + 834
All of that means that the error may not have anything to do with the code you posted, but rather with your nib and how it interacts with the properties it’s bound to.
Take a look at whether you’re using an IBOutletCollection, and if so, start debugging the things it’s bound to.