This script allows to convert an iOS framework binary to XCFramework

Framework2XCFramework.sh

# Copyright (c) 2020 Eugene Berdnikov
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# This script allows to convert an iOS framework binary to XCFramework.
# It might be useful to resolve the "Building for iOS Simulator, but the linked
# and embedded framework was built for iOS + iOS Simulator" error in Xcode 12.3.
# The script can accept working directory as a first argument.
# If no arguments passed, script looks for frameworks in the current directory.

IOS_ARCHITECTURES=(arm64 armv7 armv7s)
SIMULATOR_ARCHITECTURES=(i386 x86_64)

realpath() {
    echo "$(cd "$(dirname "$1")" || exit; pwd)/$(basename "$1")"
}

remove_architectures() {
  local FRAMEWORK_EXECUTABLE_PATH="$1"
  shift
  local ARCHITECTURES=("$@")
  for ARCH in "${ARCHITECTURES[@]}"; do
    if lipo "$FRAMEWORK_EXECUTABLE_PATH" -verify_arch "$ARCH"; then
      echo "Removing $ARCH from $(pwd)/$FRAMEWORK_EXECUTABLE_PATH"
      lipo -remove "$ARCH" -output "$FRAMEWORK_EXECUTABLE_PATH" "./$FRAMEWORK_EXECUTABLE_PATH"
    fi
  done
}

if [[ "$#" -gt 0 ]]; then
  SOURCE_PATH=$(realpath "$1")
else
  SOURCE_PATH=$(pwd)
fi

cd "$SOURCE_PATH" || exit
find "$SOURCE_PATH" -name '*.framework' -type d | while read -r FRAMEWORK_PATH; do
  echo "Handling framework in '$FRAMEWORK_PATH'"
  FRAMEWORK_EXECUTABLE_NAME=$(defaults read "$FRAMEWORK_PATH/Info.plist" "CFBundleExecutable")
  FRAMEWORK_DIRECTORY_NAME="$FRAMEWORK_EXECUTABLE_NAME.framework"

  mkdir iOS
  cp -R "$FRAMEWORK_PATH" "iOS/$FRAMEWORK_DIRECTORY_NAME"
  cd iOS || exit
  remove_architectures "$FRAMEWORK_DIRECTORY_NAME/$FRAMEWORK_EXECUTABLE_NAME" "${SIMULATOR_ARCHITECTURES[@]}"
  cd ..

  mkdir Simulator
  cp -R "$FRAMEWORK_PATH" "Simulator/$FRAMEWORK_DIRECTORY_NAME"
  cd Simulator || exit
  remove_architectures "$FRAMEWORK_DIRECTORY_NAME/$FRAMEWORK_EXECUTABLE_NAME" "${IOS_ARCHITECTURES[@]}"
  defaults write "$SOURCE_PATH/Simulator/$FRAMEWORK_DIRECTORY_NAME/Info.plist" CFBundleSupportedPlatforms -array iPhoneSimulator
  cd ..

  xcodebuild -create-xcframework -framework "iOS/$FRAMEWORK_DIRECTORY_NAME" -framework "Simulator/$FRAMEWORK_DIRECTORY_NAME" -output "$FRAMEWORK_EXECUTABLE_NAME.xcframework"
  rm -rf iOS
  rm -rf Simulator
done

This script allows to convert an iOS framework binary to XCFramework.
It might be useful to resolve the Building for iOS Simulator, but the linked and embedded framework was built for iOS + iOS Simulator error in Xcode 12.3.
The script can accept working directory as a first argument. If no arguments passed, script looks for frameworks in the current directory.
Based on @ryanthon's comment.

Nice script! Maybe add a set -e at the top to catch errors, and a #!/bin/bash shebang?

Thanks for this! The defaults was throwing errors for me because it doesn't seem to support reading/writing to arbitrary plist files anymore on the newer macOS versions.

Here's what I replaced it with:
Line 55:

FRAMEWORK_EXECUTABLE_NAME=$(/usr/libexec/PlistBuddy -c "Print :CFBundleExecutable" "$FRAMEWORK_PATH/Info.plist")

Line 68:

  /usr/libexec/PlistBuddy -c "Add :CFBundleSupportedPlatforms array iPhoneSimulator" "$SOURCE_PATH/Simulator/$FRAMEWORK_DIRECTORY_NAME/Info.plist"