当使用shake来重写UITextView并覆盖了shouldChangeCharactersInRange时，iOS超出范围崩溃

Question

我的iOS应用程序崩溃，我有崩溃报告，但我无法弄清楚崩溃的原因。奇怪的是，这个崩溃在应用程序启动后发生了一点点，并且在崩溃报告中没有我的代码的指示：

Thread 0 Crashed:
0   CoreFoundation                  0x00000002069d0ea4 __exceptionPreprocess + 228
1   libobjc.A.dylib                 0x0000000205ba0a50 objc_exception_throw + 56
2   CoreFoundation                  0x00000002068d7484 -[NSCache init] + 0
3   Foundation                      0x0000000207355b94 -[NSString substringWithRange:] + 140
4   UIKitCore                       0x00000002331cd8b8 -[NSTextStorage+ 12540088 (UIKitUndoExtensions) _undoRedoAttributedSubstringFromRange:] + 152
5   UIKitCore                       0x00000002331ce808 -[_UITextUndoOperationTyping undoRedo] + 340
6   Foundation                      0x00000002073f6734 -[_NSUndoStack popAndInvoke] + 280
7   Foundation                      0x00000002073f4790 -[NSUndoManager undoNestedGroup] + 416
8   UIKitCore                       0x0000000232ed1824 __58-[UIApplication _showEditAlertViewWithUndoManager:window:]_block_invoke.2529 + 32
9   UIKitCore                       0x0000000232618a58 -[UIAlertController _invokeHandlersForAction:] + 108
10  UIKitCore                       0x000000023261941c __103-[UIAlertController _dismissAnimated:triggeringAction:triggeredByPopoverDimmingView:dismissCompletion:]_block_invoke.477 + 28
11  UIKitCore                       0x0000000232821784 -[UIPresentationController transitionDidFinish:] + 1320
12  UIKitCore                       0x0000000232825794 __56-[UIPresentationController runTransitionForCurrentState]_block_invoke.440 + 188
13  UIKitCore                       0x0000000232923714 -[_UIViewControllerTransitionContext completeTransition:] + 116
14  UIKitCore                       0x000000023335cc4c -[UIViewAnimationBlockDelegate _didEndBlockAnimation:finished:context:] + 744
15  UIKitCore                       0x00000002333328f0 -[UIViewAnimationState sendDelegateAnimationDidStop:finished:] + 312
16  UIKitCore                       0x0000000233332edc -[UIViewAnimationState animationDidStop:finished:] + 296
17  UIKitCore                       0x0000000233332f7c -[UIViewAnimationState animationDidStop:finished:] + 456
18  QuartzCore                      0x000000020afde500 CA::Layer::run_animation_callbacks+ 1381632 (void*) + 284
19  libdispatch.dylib               0x0000000206409484 _dispatch_client_callout + 16
20  libdispatch.dylib               0x00000002063b59a4 _dispatch_main_queue_callback_4CF$VARIANT$mp + 1068
21  CoreFoundation                  0x0000000206960ce4 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12
22  CoreFoundation                  0x000000020695bbac __CFRunLoopRun + 1964
23  CoreFoundation                  0x000000020695b0e0 CFRunLoopRunSpecific + 436
24  GraphicsServices                0x0000000208bd4584 GSEventRunModal + 100
25  UIKitCore                       0x0000000232ec0c00 UIApplicationMain + 212
26  MyApplication                   0x00000001009489fc main (main.m:17)
27  libdyld.dylib                   0x0000000206419bb4 start + 4

重现步骤：

• 使用UITextField实现应用程序
• 实施UITextFieldDelegate协议并分配UITextField delegate
• 实现-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string方法从该方法返回NO
• 运行应用程序并尝试将文本粘贴到UITextField中，并观察实际上没有粘贴任何文本
• 摇动手机以触发撤消提示
• 点击提示中的撤消按钮，观察崩溃

任何帮助将不胜感激

Answer 1

如果UITextView或UITextField的文本在更改时以编程方式更改，则撤消管理器将不会更新并将跟踪错误操作。为了避免崩溃，我们应该重置undo manager，使其不包含脏操作。

[textField.undoManager removeAllActions];