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iOS13適配三指撤銷(xiāo)和文案限長(zhǎng)實(shí)例詳解

更新時(shí)間：2023年01月29日 14:12:44 作者：yuec

這篇文章主要為大家介紹了iOS13適配三指撤銷(xiāo)和文案限長(zhǎng)實(shí)例詳解，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進(jìn)步，早日升職加薪

正文

在適配iOS13的過(guò)程中，UITextField輸入中文的時(shí)候三指撤銷(xiāo)產(chǎn)生了 crash。

Bugly報(bào)錯(cuò)

NSInternalInconsistencyException
setGroupIdentifier:: _NSUndoStack 0x1206532f0 is in invalid state, calling setGroupIdentifier with no begin group mark

堆棧信息

 CoreFoundation	___exceptionPreprocess + 220
 libobjc.A.dylib	objc_exception_throw + 56
 Foundation	-[_NSUndoStack groupIdentifier]
 Foundation	-[NSUndoManager undoNestedGroup] + 240
 UIKitCore	-[UIUndoGestureInteraction undo:] + 72
 UIKitCore	-[UIKBUndoInteractionHUD performDelegateUndoAndUpdateHUDIfNeeded] + 96
 UIKitCore	-[UIKBUndoInteractionHUD controlActionUpInside:] + 152
 UIKitCore	-[UIApplication sendAction:to:from:forEvent:] + 96
 xxxxx	-[UIApplication(MemoryLeak) swizzled_sendAction:to:from:forEvent:] + 288
 UIKitCore	-[UIControl sendAction:to:forEvent:] + 240
 UIKitCore	-[UIControl _sendActionsForEvents:withEvent:] + 408
 UIKitCore	-[UIControl touchesEnded:withEvent:] + 520
 UIKitCore	-[UIWindow _sendTouchesForEvent:] + 2324
 UIKitCore	-[UIWindow sendEvent:] + 3352
 UIKitCore	-[UIApplication sendEvent:] + 336
 UIKitCore	___dispatchPreprocessedEventFromEventQueue + 5880
 UIKitCore	___handleEventQueueInternal + 4924
 UIKitCore	___handleHIDEventFetcherDrain + 108
 CoreFoundation	___CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24
 CoreFoundation	___CFRunLoopDoSource0 + 80
 CoreFoundation	___CFRunLoopDoSources0 + 180
 CoreFoundation	___CFRunLoopRun + 1080
 CoreFoundation	CFRunLoopRunSpecific + 464
 GraphicsServices	GSEventRunModal + 104
 UIKitCore	UIApplicationMain + 1936
 xxxxx	main + 148
 libdyld.dylib	_start + 4

問(wèn)題定位

沒(méi)有太多思路的時(shí)候，通過(guò)注釋代碼，最終定位到了問(wèn)題所在。

[self addTarget:observer
         action:@selector(textChange:)
forControlEvents:UIControlEventEditingChanged];

- (void)textChange:(UITextField *)textField {
    ... ... 
    UITextRange *selectedRange = [textField markedTextRange];
    if (!selectedRange || !selectedRange.start) {
        if (destText.length > maxLength) {
            textField.text = [destText substringToIndex:maxLength];
        }
    }
}

這段代碼在輸入的時(shí)候會(huì)限制文案的長(zhǎng)度。三指撤銷(xiāo)會(huì)觸發(fā)UIControlEventEditingChanged事件，執(zhí)行textChange，此時(shí)獲取到的markedTextRange是nil，即便是存在markedText。這就導(dǎo)致UITextField的text有可能會(huì)被修改。修改文案后再繼續(xù)執(zhí)行撤銷(xiāo)操作，必定會(huì)產(chǎn)生 crash。

解決方案

將文案判長(zhǎng)和截取異步添加到主隊(duì)列，在下一個(gè)runloop執(zhí)行。

- (void)textChange:(UITextField *)textField {
    dispatch_async(dispatch_get_main_queue(), ^{
        ... ...
    });
}

數(shù)字截?cái)嗪?crash

數(shù)字輸入限制長(zhǎng)度后，超過(guò)長(zhǎng)度后繼續(xù)輸入，這個(gè)時(shí)候撤銷(xiāo)也會(huì)產(chǎn)生crash，而且上面的方法不可行。目前想到的方案是在UITextField的回調(diào)方法進(jìn)行輸入的攔截。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    /// 輸入數(shù)字后截取字符串仍舊可以觸發(fā)撤銷(xiāo)操作導(dǎo)致crash, 在這里攔截一下
    if (textField.keyboardType == UIKeyboardTypeNumberPad
        && range.location >= textField.tt_maxLength) {
            return NO;
    }
    return YES;
}

以上就是iOS13適配三指撤銷(xiāo)和文案限長(zhǎng)實(shí)例詳解的詳細(xì)內(nèi)容，更多關(guān)于iOS13適配三指撤銷(xiāo)文案限長(zhǎng)的資料請(qǐng)關(guān)注腳本之家其它相關(guān)文章！

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