Creating iOS Framework for single platform is giving error.

[DRK1004]

Steps to Reproduce

I have .net library and trying to create a ios framework for single platform ( i.e either arm64 or x86_64) from that. To do that I used the either of below commands:
objcgen XXX.iOS.dll --target=framework --platform=iOS --outdir=iOS -c --abi=arm64 -d --nativeexception

Expected Behavior

Single framework for arm64 should be created.

Actual Behavior

Observed error:
error MT5209: Native linking error: warning: ignoring file XXXX.a, building for iOS Simulator-i386 but attempting to link with file built for iOS-arm64

Environment

Embeddinator-4000 v0.1 (0.4: 7664197)
Found Mono 6.10.0.104 (between 5.4.1.7 and 5.4.1.7)
Found Xamarin.iOS 13.20.2.2 (between 11.6.1.3 and 11.6.1.3)
XCode 12.2
MacOS : Catalina version 10.15.7

Build Logs

Parsing assemblies...
Parsed 'XXX.iOS.dll'
Processing assemblies...
54 types found
Generating binding code...
Generated: iOS/bindings.h
Generated: iOS/bindings-private.h
Generated: iOS/bindings.m
Generated: iOS/bindings.xml
Generated: iOS/embeddinator.h
Generated: iOS/glib.h
Generated: iOS/mono_embeddinator.h
Generated: iOS/mono-support.h
Generated: iOS/objc-support.h
Generated: iOS/glib.c
Generated: iOS/mono_embeddinator.c
Generated: iOS/objc-support.m
Generated: iOS/Make.config
Compiling binding code...
Found Mono 6.10.0.104 (between 5.4.1.7 and 5.4.1.7)
Found Xamarin.iOS 13.20.2.2 (between 11.6.1.3 and 11.6.1.3)

xcode-select -p
xcrun clang -g -O0 -DNATIVEEXCEPTION -fobjc-arc -ObjC -Wall -arch arm64 -isysroot XXX/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk -miphoneos-version-min=8.0 -I/Library/Frameworks/Xamarin.iOS.framework/Versions/Current/SDKs/MonoTouch.iphoneos.sdk/usr/include -DXAMARIN_IOS -DMONO_EMBEDDINATOR_DLL_EXPORT -c iOS/glib.c -o iOS/arm64/glib.o
xcrun clang -g -O0 -DNATIVEEXCEPTION -fobjc-arc -ObjC -Wall -arch arm64 -isysroot XXX/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk -miphoneos-version-min=8.0 -I/Library/Frameworks/Xamarin.iOS.framework/Versions/Current/SDKs/MonoTouch.iphoneos.sdk/usr/include -DXAMARIN_IOS -DMONO_EMBEDDINATOR_DLL_EXPORT -c iOS/mono_embeddinator.c -o iOS/arm64/mono_embeddinator.o
xcrun clang -g -O0 -DNATIVEEXCEPTION -fobjc-arc -ObjC -Wall -arch arm64 -isysroot XXX/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk -miphoneos-version-min=8.0 -I/Library/Frameworks/Xamarin.iOS.framework/Versions/Current/SDKs/MonoTouch.iphoneos.sdk/usr/include -DXAMARIN_IOS -DMONO_EMBEDDINATOR_DLL_EXPORT -c iOS/objc-support.m -o iOS/arm64/objc-support.o
xcrun clang -g -O0 -DNATIVEEXCEPTION -fobjc-arc -ObjC -Wall -arch arm64 -isysroot XXX/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk -miphoneos-version-min=8.0 -I/Library/Frameworks/Xamarin.iOS.framework/Versions/Current/SDKs/MonoTouch.iphoneos.sdk/usr/include -DXAMARIN_IOS -DMONO_EMBEDDINATOR_DLL_EXPORT -c iOS/bindings.m -o iOS/arm64/bindings.o
xcrun ar cru iOS/arm64/XXX.iOS.a iOS/arm64/glib.o iOS/arm64/mono_embeddinator.o iOS/arm64/objc-support.o iOS/arm64/bindings.o
xcrun --show-sdk-version --sdk iphoneos
/Library/Frameworks/Xamarin.iOS.framework/Versions/Current/bin/mtouch --dev XXX.iOS --abi=arm64 --sdkroot XXUSERXX/Xcode_12.2.app --targetver 8.0 --dsym:false --msym:false --embeddinator XXX.iOS/bin/Release/XXX.iOS.dll -r:/Library/Frameworks/Xamarin.iOS.framework/Versions/Current/lib/mono/Xamarin.iOS/Xamarin.iOS.dll --sdk 14.2 --linksdkonly --xml=iOS/bindings.xml --registrar:static --cache XXX.iOS/bin/Release/iOS/iPhoneOS/build-cache --debug --assembly-build-target=@ALL=framework=XXX.iOS.framework --target-framework Xamarin.iOS,v1.0 "--gcc_flags=-force_load XXX.iOS.a" --marshal-managed-exceptions=throwobjectivecexception
xcrun --show-sdk-version --sdk iphonesimulator
/Library/Frameworks/Xamarin.iOS.framework/Versions/Current/bin/mtouch --sim XXX.iOS/bin/Release/iOS/iPhoneSimulator/XXX.iOS --abi= --sdkroot XXUSERXX/Xcode_12.2.app --targetver 8.0 --dsym:false --msym:false --embeddinator XXX.iOS/bin/Release/XXX.iOS.dll -r:/Library/Frameworks/Xamarin.iOS.framework/Versions/Current/lib/mono/Xamarin.iOS/Xamarin.iOS.dll --sdk 14.2 --linksdkonly --xml=iOS/bindings.xml --registrar:static --cache XXX.iOS/bin/Release/iOS/iPhoneSimulator/build-cache --debug --assembly-build-target=@ALL=framework=XXX.iOS.framework --target-framework Xamarin.iOS,v1.0 "--gcc_flags=-force_load XXX.iOS/bin/Release/iOS/iPhoneSimulator/XXX.iOS.a" --marshal-managed-exceptions=throwobjectivecexception
Xamarin.iOS 13.20.2.2 (d16-7): 817b6f72a using framework: XXX/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator14.2.sdk
warning MT0030: The executable name (XXX.iOS) and the app name (XXX.iOS) are different, this may prevent crash logs from getting symbolicated properly.

Process exited with code 1, command:
error MT5209: Native linking error: warning: -pie being ignored. It is only used when linking a main executable

error MT5209: Native linking error: warning: ignoring file XXX.iOS/bin/Release/iOS/iPhoneSimulator/XXX.iOS.a, building for iOS Simulator-i386 but attempting to link with file built for iOS-arm64

error MT5210: Native linking failed, undefined symbol: _xamarin_embeddinator_initialize. Please verify that all the necessary frameworks have been referenced and native libraries are properly linked in.

warning MT5215: References to 'System' might require additional -framework=XXX or -lXXX instructions to the native linker

warning MT5215: References to 'kernel32' might require additional -framework=XXX or -lXXX instructions to the native linker

warning MT5215: References to 'libdl' might require additional -framework=XXX or -lXXX instructions to the native linker

warning MT5215: References to 'MathNET.Numerics.OpenBLAS' might require additional -framework=XXX or -lXXX instructions to the native linker

warning MT5215: References to 'MathNet.Numerics.MKL' might require additional -framework=XXX or -lXXX instructions to the native linker

warning MT5215: References to 'MathNet.Numerics.CUDA' might require additional -framework=XXX or -lXXX instructions to the native linker

warning MT5215: References to 'kernel32' might require additional -framework=XXX or -lXXX instructions to the native linker

warning MT5215: References to 'Advapi32' might require additional -framework=XXX or -lXXX instructions to the native linker

error MT5201: Native linking failed. Please review the build log and the user flags provided to gcc: -force_load XXX.iOS/bin/Release/iOS/iPhoneSimulator/XXX.iOS.a

XXUSERXX/Xcode_12.2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -framework Security -framework UIKit -framework Foundation -weak_framework CoreFoundation -weak_framework CFNetwork -weak_framework GSS -Xlinker -rpath -Xlinker @executable_path/ XXX.iOS/bin/Release/iOS/iPhoneSimulator/build-cache/i386/registrar.o XXX.iOS/bin/Release/iOS/iPhoneSimulator/build-cache/i386/main.o /Library/Frameworks/Xamarin.iOS.framework/Versions/13.20.2.2/SDKs/MonoTouch.iphonesimulator.sdk/usr/lib/libmonosgen-2.0.a /Library/Frameworks/Xamarin.iOS.framework/Versions/13.20.2.2/SDKs/MonoTouch.iphonesimulator.sdk/usr/lib/libxamarin-debug.a /Library/Frameworks/Xamarin.iOS.framework/Versions/13.20.2.2/SDKs/MonoTouch.iphonesimulator.sdk/usr/lib/libmono-native-compat.a -lsqlite3 -Wl,-pie -arch i386 -gdwarf-2 -std=c++14 -I/Library/Frameworks/Xamarin.iOS.framework/Versions/13.20.2.2/SDKs/MonoTouch.iphonesimulator.sdk/usr/include -isysroot XXX/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator14.2.sdk -Qunused-arguments -fobjc-legacy-dispatch -fobjc-abi-version=2 -mios-simulator-version-min=8.0 -lz -liconv -lz -o XXX.iOS/bin/Release/iOS/iPhoneSimulator/XXX.iOS/XXX.iOS -shared -install_name @rpath/XXX.iOS.framework/XXX.iOS -force_load XXX.iOS/bin/Release/iOS/iPhoneSimulator/XXX.iOS.a -u _SystemNative_ConvertErrorPlatformToPal -u _SystemNative_ConvertErrorPalToPlatform -u _SystemNative_StrErrorR -u _SystemNative_GetNonCryptographicallySecureRandomBytes -u _SystemNative_OpenDir -u _SystemNative_GetReadDirRBufferSize -u _SystemNative_ReadDirR -u _SystemNative_CloseDir -u _SystemNative_ReadLink -u _SystemNative_Stat2 -u _SystemNative_LStat2 -u _SystemNative_Symlink -u _SystemNative_CopyFile -u _SystemNative_GetEGid -u _SystemNative_GetEUid -u _SystemNative_MkDir -u _SystemNative_Rename -u _SystemNative_RmDir -u _SystemNative_UTimes -u _SystemNative_Unlink -u _xamarin_timezone_get_local_name -u _xamarin_timezone_get_data -u _xamarin_GetFolderPath -u _xamarin_log -u _xamarin_start_wwan -u _xamarin_find_protocol_wrapper_type -u _xamarin_get_block_descriptor -u _mono_pmip -u _xamarin_dyn_objc_msgSend -u _xamarin_dyn_objc_msgSendSuper -u _xamarin_dyn_objc_msgSend_stret -u _xamarin_dyn_objc_msgSendSuper_stret
ld: warning: -pie being ignored. It is only used when linking a main executable
ld: warning: ignoring file XXX.iOS/bin/Release/iOS/iPhoneSimulator/XXX.iOS.a, building for iOS Simulator-i386 but attempting to link with file built for iOS-arm64
Undefined symbols for architecture i386:
"_xamarin_embeddinator_initialize", referenced from:
native_to_managed_trampoline_1(objc_object*, objc_selector*, _MonoMethod**, objc_object*, unsigned int) in registrar.o
native_to_managed_trampoline_2(objc_object*, objc_selector*, _MonoMethod**, void*, unsigned int) in registrar.o
native_to_managed_trampoline_3(objc_object*, objc_selector*, _MonoMethod**, unsigned int) in registrar.o
native_to_managed_trampoline_4(objc_object*, objc_selector*, _MonoMethod**, bool*, unsigned int) in registrar.o
native_to_managed_trampoline_5(objc_object*, objc_selector*, _MonoMethod**, objc_object*, unsigned int) in registrar.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

[rolfbjarne]

It's not possible to build for only simulator or device at the moment, you have to build for both (and select at least one architecture for each).

Relevant code:

Embeddinator-4000/objcgen/embedder.cs

Lines 359 to 363 in 3bbe342

	case Platform.iOS:
	build_infos = new BuildInfo[] {
	new BuildInfo { Sdk = "iPhoneOS", Architectures = new string [] { "armv7", "armv7s", "arm64" }, SdkName = "iphoneos", MinVersion = "8.0", XamariniOSSDK = "MonoTouch.iphoneos.sdk", CompilerFlags = GetBitcodeFlag(defaultsToEnable: false), LinkerFlags = GetBitcodeFlag(defaultsToEnable: false) },
	new BuildInfo { Sdk = "iPhoneSimulator", Architectures = new string [] { "i386", "x86_64" }, SdkName = "ios-simulator", MinVersion = "8.0", XamariniOSSDK = "MonoTouch.iphonesimulator.sdk" },
	};

[DRK1004]

XCFrameworks are required for Xcode 12.3+ . I have already created #790 for supporting XCFramework. As a workaround for now, I am trying to build one platform at a time, so that I can use those frameworks to create an XCFramework.

Let me know if you have any other suggestions for creating XCFrameworks.