在什么情况下，UITableView在-[UITableViewDelegate tableView:titleForDeleteConfirmationButtonForRowAtIndexPath:]中的行中给出-1或NSUIntegerMax？
下面是用户的崩溃日志。
OS Version: iPhone OS 9.2.1 (13D15)
Application Specific Information:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'no object at index 18446744073709551615 in section at index 0'
Last Exception Backtrace:
0 CoreFoundation 0x0000000181241900 __exceptionPreprocess + 124
1 libobjc.A.dylib 0x00000001808aff80 objc_exception_throw + 56
2 CoreData 0x0000000182cc50bc -[NSFetchedResultsController objectAtIndexPath:] + 456
3 My App 0x000000010022c678 -[MyViewController tableView:titleForDeleteConfirmationButtonForRowAtIndexPath:] (MyViewController.m:560)
4 UIKit 0x0000000186145174 -[UITableView _titleForDeleteConfirmationButtonForRowAtIndexPath:] + 160
5 UIKit 0x00000001862756f4 -[UITableView _deleteConfirmationButtonForRowAtIndexPath:] + 116
6 UIKit 0x0000000186275cf4 -[UITableView _swipeActionButtonsForRowAtIndexPath:] + 824
7 UIKit 0x0000000186275998 -[UITableView _swipeActionButtons] + 92
8 UIKit 0x0000000186144bd8 __32-[UITableViewCell _beginSwiping]_block_invoke + 120
9 UIKit 0x0000000185f42964 +[UIView(Animation) performWithoutAnimation:] + 80
10 UIKit 0x0000000186144b48 -[UITableViewCell _beginSwiping] + 96
11 UIKit 0x0000000186272320 -[UITableViewWrapperView handleSwipeBeginning:] + 256
12 UIKit 0x00000001864b4ea4 _UIGestureRecognizerSendTargetActions + 396
13 UIKit 0x00000001860d85b8 _UIGestureRecognizerSendActions + 172
14 UIKit 0x0000000185f669b0 -[UIGestureRecognizer _updateGestureWithEvent:buttonEvent:] + 784
15 UIKit 0x00000001864b63bc ___UIGestureRecognizerUpdate_block_invoke904 + 72
16 UIKit 0x0000000185f25b58 _UIGestureRecognizerRemoveObjectsFromArrayAndApplyBlocks + 372
17 UIKit 0x0000000185f228dc _UIGestureRecognizerUpdate + 2404
18 UIKit 0x0000000185f64820 -[UIWindow _sendGesturesForEvent:] + 1132
19 UIKit 0x0000000185f63e1c -[UIWindow sendEvent:] + 764
20 UIKit 0x0000000185f344cc -[UIApplication sendEvent:] + 248
21 UIKit 0x0000000185f32794 _UIApplicationHandleEventQueue + 5528
22 CoreFoundation 0x00000001811f8efc __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24
23 CoreFoundation 0x00000001811f8990 __CFRunLoopDoSources0 + 540
24 CoreFoundation 0x00000001811f6690 __CFRunLoopRun + 724
25 CoreFoundation 0x0000000181125680 CFRunLoopRunSpecific + 384
26 GraphicsServices 0x0000000182634088 GSEventRunModal + 180
27 UIKit 0x0000000185f9cd90 UIApplicationMain + 204
28 My App 0x00000001000a926c main (main.m:16)
29 ??? 0x0000000180cc68b8 0x0 + 0
- (NSString *)tableView:(UITableView *)tableView titleForDeleteConfirmationButtonForRowAtIndexPath:(NSIndexPath *)indexPath
{
MyMessage *message = [self messageAtIndex:indexPath.row];
if ([message.senderUid isEqualToString:mUid])
return NSLocalizedString(@"Delete", nil);
else
return NSLocalizedString(@"Hide", nil);
}
- (MyMessage *)messageAtIndex:(NSInteger)index
{
return [mMessagesController objectAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0]];
}
最佳答案
indexPath.row和indexPath.section都是NSUInteger(无符号整数)，这意味着它严格是正数。如果减去并最终变为负数，它将跳至NSUIntegerMax。这使得必须小心涉及索引路径的算法。
当对等于零的row - 1执行row时，将获得NSUIntegerMax。
关于ios - -[UITableViewDelegate tableView:titleForDeleteConfirmationButtonForRowAtIndexPath:]给定的第-1行或NSUIntegerMax，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/36546037/