Unity项目适配Xcode13编译报错：Undefined symbol问题求助

问题背景 #

Unity开发的游戏已在Google Play上线，Android端Admob广告、内购功能正常。尝试发布到App Store时，因旧Mac仅支持Xcode 13.0，编译iOS项目时出现大量Undefined symbol: _objc_msgSend$xxx类错误（完整错误列表见下方）。

完整错误列表 #

Undefined symbol: _objc_msgSend$initWithURL:resolvingAgainstBaseURL:
Undefined symbol: _objc_msgSend$queryItems
Undefined symbol: _objc_msgSend$initWithBytes:length:
Undefined symbol: _objc_msgSend$initMessageInfoFn
Undefined symbol: _objc_msgSend$copyMessageInfoFn
Undefined symbol: _objc_msgSend$showWithCompletionHandler:
Undefined symbol: _objc_msgSend$initWithConsentFormClientReference:
Undefined symbol: _objc_msgSend$isConsentFormAvailable
Undefined symbol: _objc_msgSend$initWithConsentInformationClientReference:
Undefined symbol: _objc_msgSend$adSourceInstanceName
Undefined symbol: _objc_msgSend$adSourceName
Undefined symbol: _objc_msgSend$extrasDictionary
Undefined symbol: _objc_msgSend$responseIdentifier
Undefined symbol: _objc_msgSend$adNetworkClassName
Undefined symbol: _objc_msgSend$loadWithAdUnitID:orientation:request:
Undefined symbol: _objc_msgSend$setCustomAdPosition:
Undefined symbol: _objc_msgSend$setAdPosition:
Undefined symbol: _objc_msgSend$setExtraWithKey:value:
Undefined symbol: _objc_msgSend$adNetworkExtrasWithDictionary:
Undefined symbol: _objc_msgSend$setCustomRewardString:
Undefined symbol: _objc_msgSend$setUserIdentifier:
Undefined symbol: _objc_msgSend$addKeyword:
Undefined symbol: _objc_msgSend$maxAdContentRating
Undefined symbol: _objc_msgSend$setMaxAdContentRating:
Undefined symbol: _objc_msgSend$tagForUnderAgeOfConsent:
Undefined symbol: _objc_msgSend$tagForChildDirectedTreatment:
Undefined symbol: _objc_msgSend$sameAppKeyEnabled
Undefined symbol: _objc_msgSend$setSameAppKeyEnabled:
Undefined symbol: _objc_msgSend$heightInPixels
Undefined symbol: _objc_msgSend$setDidEarnRewardCallback:
Undefined symbol: _objc_msgSend$setAdFailedCallback:
Undefined symbol: _objc_msgSend$setDidDismissCallback:
Undefined symbol: _objc_msgSend$setAdImpressionCallback:
Undefined symbol: _objc_msgSend$show
Undefined symbol: _objc_msgSend$setAdClickedCallback:
Undefined symbol: _objc_msgSend$setAdLoadedCallback:
Undefined symbol: _objc_msgSend$setAdFailedToLoadCallback:
Undefined symbol: _objc_msgSend$setPaidEventCallback:
Undefined symbol: _objc_msgSend$setAdFailedToPresentFullScreenContentCallback:
Undefined symbol: _objc_msgSend$setAdWillPresentFullScreenContentCallback:
Undefined symbol: _objc_msgSend$initWithRewardedInterstitialAdClientReference:
Undefined symbol: _objc_msgSend$initWithSmartBannerSizeAndBannerClientReference:adUnitID:adPosition:
Undefined symbol: _objc_msgSend$initWithBannerClientReference:adUnitID:width:height:adPosition:
Undefined symbol: _objc_msgSend$initWithAppOpenAdClientReference:
Undefined symbol: _objc_msgSend$setPauseOnBackground:
Undefined symbol: _objc_msgSend$setApplicationMuted:
Undefined symbol: _objc_msgSend$state
Undefined symbol: _objc_msgSend$gadu_referenceKey
Undefined symbol: _objc_msgSend$startWithCompletionHandler:
Undefined symbol: _objc_msgSend$environment
Undefined symbol: _objc_msgSend$indexOfObject:
Undefined symbol: _objc_msgSend$price
Undefined symbol: _objc_msgSend$priceLocale
Undefined symbol: _objc_msgSend$transactionID
Undefined symbol: _objc_msgSend$originalTransactionID
Undefined symbol: _objc_msgSend$isIntroductoryOffer
Undefined symbol: _objc_msgSend$setDateFormat:
Undefined symbol: _objc_msgSend$timeZoneForSecondsFromGMT:
Undefined symbol: _objc_msgSend$dateFromString:
Undefined symbol: _objc_msgSend$compare:options:
Undefined symbol: _objc_msgSend$dictionaryWithObjects:forKeys:
Undefined symbol: _objc_msgSend$moveItemAtPath:toPath:error:
Undefined symbol: _objc_msgSend$pathExtension
Undefined symbol: _objc_msgSend$stringByAppendingPathExtension:
Undefined symbol: _objc_msgSend$initFileURLWithPath:
Undefined symbol: _objc_msgSend$maxParametersPerFilter
Undefined symbol: _objc_msgSend$maxFiltersPerAudience
Undefined symbol: _objc_msgSend$dateWithTimeIntervalSince1970:
Undefined symbol: _objc_msgSend$timeIntervalSinceDate:
Undefined symbol: _objc_msgSend$adapterStatusesByClassName
Undefined symbol: _objc_msgSend$compare:options:range:locale:
Undefined symbol: _objc_msgSend$isValidInternalEventParameterName:failureCode:
Undefined symbol: _objc_msgSend$sortedArrayUsingComparator:
Undefined symbol: _objc_msgSend$itemScopedCustomParameterEnabled
Undefined symbol: _objc_msgSend$maxItemScopedCustomParameters
Undefined symbol: _objc_msgSend$isValidArrayParamItem:failureCode:
Undefined symbol: _objc_msgSend$setCenter:
Undefined symbol: _objc_msgSend$safeAreaLayoutGuide
Undefined symbol: _objc_msgSend$layoutFrame
Undefined symbol: _objc_msgSend$isOperatingSystemAtLeastVersion:
Undefined symbol: _objc_msgSend$setAppOpenAd:
Undefined symbol: _objc_msgSend$appOpenAd
Undefined symbol: _objc_msgSend$loadWithAdUnitID:request:orientation:completionHandler:
Undefined symbol: _objc_msgSend$setRewardedInterstitialAd:
Undefined symbol: _objc_msgSend$rewardedInterstitialAd
Undefined symbol: _objc_msgSend$rewardedInterstitialAdClient
Undefined symbol: _objc_msgSend$setAdditionalParameters:
Undefined symbol: _objc_msgSend$interstitialClient
Undefined symbol: _objc_msgSend$adDidDismissFullScreenContentCallback
Undefined symbol: _objc_msgSend$pauseOnBackground
Undefined symbol: _objc_msgSend$adWillPresentFullScreenContentCallback
Undefined symbol: _objc_msgSend$adFailedToPresentFullScreenContentCallback
Undefined symbol: _objc_msgSend$adReward
Undefined symbol: _objc_msgSend$rewardedAd
Undefined symbol: _objc_msgSend$presentFromRootViewController:userDidEarnRewardHandler:
Undefined symbol: _objc_msgSend$setFullScreenContentDelegate:
Undefined symbol: _objc_msgSend$adLoadedCallback
Undefined symbol: _objc_msgSend$setTagForChildDirectedTreatment:
Undefined symbol: _objc_msgSend$rewardedAdClient
Undefined symbol: _objc_msgSend$adImpressionCallback

解决方案 #

1. 降级适配Xcode 13的第三方插件版本 #

这些错误大多来自Admob、Unity IAP等插件的SDK与Xcode 13不兼容。新版本的Google Mobile Ads SDK已不再支持Xcode 13，需降级到适配版本：

• Google Mobile Ads Unity Plugin：选择8.3.0及以下版本（该版本适配Xcode 13及iOS 15）
• Unity IAP：选择4.4.0及以下版本，确保与Xcode 13的iOS SDK兼容

2. 调整Unity iOS构建配置 #

• 在Unity编辑器的Player Settings > iOS > Other Settings中，设置Target iOS Version为15.0（Xcode 13支持的最高iOS版本）
• 关闭Bitcode选项（部分新版本SDK默认不支持Bitcode，Xcode 13处理高版本SDK的Bitcode会引发符号缺失）

3. 修复Xcode项目链接设置 #

• 打开生成的Xcode项目，进入Build Settings，找到Other Linker Flags，添加-ObjC参数（确保静态库中的Objective-C类别和符号被正确链接）
• 确认项目已添加必要的系统框架：StoreKit、AdSupport、CoreTelephony、SystemConfiguration（Admob和内购功能依赖这些框架）

4. 清理缓存并重新构建 #

• 删除Unity项目根目录下的Library文件夹，重新生成iOS项目（清除旧的缓存文件，避免插件版本冲突）
• 在Xcode中执行Cmd+Shift+K清理Build Folder，再重新编译项目

5. 检查插件的iOS依赖配置 #

• 在Unity的Package Manager中，确认Admob和IAP插件的iOS依赖已正确导入，没有重复或缺失的库文件
• 打开Xcode项目的Frameworks, Libraries, and Embedded Content面板，确保所有插件的.framework文件都设置为Embed & Sign

内容的提问来源于stack exchange，提问作者Emre BORAN