Xamarin.Forms で iOS のプロジェクトをビルドしたら以下のようなエラーが発生しました。
/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/iOS/Xamarin.iOS.Common.targets(3,3): Error: ibtool exited with code 255 (PrismSample2.iOS)
最初は訳が分からなかったのですが、Xcode のアップデート中だとビルドに失敗する模様。
Xcode のアップデートを最後まで完了させたらエラーは発生しなくなりました。
なお、上記エラー以外にも以下のようなエラーが発生していましたが、こちらも解消しました。
/Users/xxx/Projects/PrismSample2/PrismSample2.iOS/Resources/LaunchScreen.xib: Error: 2018-09-18 22:50:36.285 ibtoold[46678:42176806] +[SimServiceContext serviceContextForDeveloperDir:error:]: unrecognized selector sent to class 0x119e2fc00 2018-09-18 22:50:36.317 ibtoold[46678:42176806] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[SimServiceContext serviceContextForDeveloperDir:error:]: unrecognized selector sent to class 0x119e2fc00' *** First throw call stack: ( 0 CoreFoundation 0x00007fff367a22db __exceptionPreprocess + 171 1 libobjc.A.dylib 0x00007fff5d943c76 objc_exception_throw + 48 2 CoreFoundation 0x00007fff3683acf4 +[NSObject(NSObject) doesNotRecognizeSelector:] + 132 3 CoreFoundation 0x00007fff36718820 ___forwarding___ + 1456 4 CoreFoundation 0x00007fff367181e8 _CF_forwarding_prep_0 + 120 5 IDEInterfaceBuilderCocoaTouchIntegration 0x00000001199bf2dc __IBSharedInterfaceBuilderSpecificSimulatorServiceContext_block_invoke_2 + 162 6 IDEInterfaceBuilderCocoaTouchIntegration 0x00000001199bf20e __IBSharedInterfaceBuilderSpecificSimulatorServiceContext_block_invoke + 28 7 libdispatch.dylib 0x00007fff5e523db8 _dispatch_client_callout + 8 8 libdispatch.dylib 0x00007fff5e523d6b dispatch_once_f + 41 9 IDEInterfaceBuilderCocoaTouchIntegration 0x00000001199bf1ad IBSharedInterfaceBuilderSpecificSimulatorServiceContext + 1165 10 IDEInterfaceBuilderCocoaTouchIntegration 0x000000011989d03e -[IBCocoaTouchIdiom trySimDeviceTypeForIdentifier:error:] + 56 11 IDEInterfaceBuilderCocoaTouchIntegration 0x000000011989d1f9 -[IBCocoaTouchIdiom simDeviceTypeForToolDescription:error:] + 153 12 IDEInterfaceBuilderCocoaTouchIntegration 0x0000000119956ea4 -[IBCocoaTouchPlatformToolDescription preferredDeviceTypeReturningError:] + 114 13 IDEInterfaceBuilderCocoaTouchIntegration 0x00000001198722f7 -[IBCocoaTouchToolManager executionContextForDescription:error:] + 225 14 IDEInterfaceBuilderKit 0x000000010ab07e41 -[IBAbstractInterfaceBuilderPlatformToolManager _determineContextsForLaunchingToolWithDescription:returningLaunchContext:returningExecutionContext:returningFailureContext:error:forReason:] + 136 15 IDEInterfaceBuilderKit 0x000000010ab0815f -[IBAbstractInterfaceBuilderPlatformToolManager launchNewToolWithDescription:error:forReason:] + 154 16 IDEInterfaceBuilderCocoaTouchIntegration 0x0000000119872e04 -[IBCocoaTouchToolManager launchNewToolWithDescription:error:forReason:] + 89 17 IDEInterfaceBuilderKit 0x000000010ab05d66 -[IBAbstractInterfaceBuilderPlatformToolManager cachedToolIncrementBusyWithDescription:error:forReason:] + 258 18 IDEInterfaceBuilderCocoaTouchIntegration 0x0000000119872ca0 -[IBCocoaTouchToolManager cachedToolIncrementBusyWithDescription:error:forReason:] + 89 19 IDEInterfaceBuilderCocoaTouchIntegration 0x00000001198f04ce __122-[IBCocoaTouchXIBDocumentCompiler compiledKeyedObjectsDataWithMarshallingContext:archivingContext:diagnosticsBlock:error:]_block_invoke.95 + 267 20 libdispatch.dylib 0x00007fff5e523db8 _dispatch_client_callout + 8 21 libdispatch.dylib 0x00007fff5e5371e1 _dispatch_queue_barrier_sync_invoke_and_complete + 60 22 DVTFoundation 0x000000010b7613db DVTDispatchSync + 208 23 IDEInterfaceBuilderCocoaTouchIntegration 0x00000001198efe26 -[IBCocoaTouchXIBDocumentCompiler compiledKeyedObjectsDataWithMarshallingContext:archivingContext:diagnosticsBlock:error:] + 3436 24 IDEInterfaceBuilderCocoaTouchIntegration 0x00000001198f163c __121-[IBCocoaTouchXIBDocumentCompiler compiledPackageWithOptions:marshallingContext:archivingContext:diagnosticsBlock:error:]_block_invoke + 72 25 IDEInterfaceBuilderKit 0x000000010abada43 __85-[IBDocumentCompiler invokeWithIntermediateDocumentOfTargetRuntime:alwaysCopy:block:]_block_invoke + 137 26 IDEInterfaceBuilderKit 0x000000010abad7b2 -[IBDocumentCompiler invokeWithIntermediateDocument:] + 244 27 IDEInterfaceBuilderKit 0x000000010abad970 -[IBDocumentCompiler invokeWithIntermediateDocumentOfTargetRuntime:alwaysCopy:block:] + 244 28 IDEInterfaceBuilderCocoaTouchIntegration 0x00000001198f0c56 -[IBCocoaTouchXIBDocumentCompiler compiledPackageWithOptions:marshallingContext:archivingContext:diagnosticsBlock:error:] + 696 29 IDEInterfaceBuilderCocoaTouchIntegration 0x00000001198f195b -[IBCocoaTouchXIBDocumentCompiler compileWithOptions:error:] + 380 30 IDEInterfaceBuilderKit 0x000000010abadb4a +[IBDocumentCompiler compileContentsOfDocument:options:error:] + 123 31 IDEInterfaceBuilderKit 0x000000010ab67076 __47-[IBDocument compiledPackageWithOptions:error:]_block_invoke + 56 32 IDEInterfaceBuilderKit 0x000000010abab2b9 -[IBDocumentAutolayoutManager ignoreAutolayoutStatusInvalidationDuring:] + 27 33 IDEInterfaceBuilderKit 0x000000010ab66fca -[IBDocument compiledPackageWithOptions:error:] + 227 34 IDEInterfaceBuilderKit 0x000000010ab67315 -[IBDocument compileAndWriteToPath:withOptions:error:] + 180 35 ibtoold 0x000000010a9c4e73 IBCompileDocumentForSingleTargetDevice + 211 36 ibtoold 0x000000010a9c073c -[IBCLIInterfaceBuilderToolPersona invokeArguments:outputDictionary:] + 26169 37 ibtoold 0x000000010a9c367e -[IBCLIInterfaceBuilderToolPersona runSingleInvocation:outputtingToFileHandle:andVerifyingEnvironment:] + 3171 38 ibtoold 0x000000010a9c70e7 IBCLIServerRunSingleInvocation + 520 39 ibtoold 0x000000010a9c773e __IBCLIServerRunSingleInvocationWithIODirectedAtPipesAndUnlinkOnSuccess_block_invoke_2 + 34 40 ibtoold 0x000000010a9c760c __IBCLIServerRunSingleInvocationWithIODirectedAtPipesAndUnlinkOnSuccess_block_invoke + 857 41 ibtoold 0x000000010a9b63f5 -[IBCLIErrorForwarder forwardErrorOutputToDescriptor:whileInvokingBlock:] + 110 42 ibtoold 0x000000010a9c6c9d IBCLIServerRunSingleInvocationWithIODirectedAtPipesAndUnlinkOnSuccess + 581 43 ibtoold 0x000000010a9c5a7d main + 2673 44 libdyld.dylib 0x00007fff5e55d015 start + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException (PrismSample2.iOS)