Xcode – Flutter – Code signing "App.framework" failed

Here is how you can solve this error:
You must add script to your xcode that will remove the non used code of 3rd party libraries.
When you open your flutter iOS project in xcode you will see in the build phases section that flutter already has a script in place. Do not mess with this script, instead you will add a new one .
Like here is this image:

Then you will have something like this:

After this open the run script and place this code:

# Type a script or drag a script file from your workspace to insert its path.APP_PATH="${TARGET_BUILD_DIR}/${WRAPPER_NAME}"
# This script loops through the frameworks embedded in the application and
# removes unused architectures.

find "$APP_PATH" -name 'FRAMEWORK_NAME*.framework' -type d | while read -r
FRAMEWORK
do
FRAMEWORK_EXECUTABLE_NAME=$(defaults read "$FRAMEWORK/Info.plist" CFBundleExecutable)
FRAMEWORK_EXECUTABLE_PATH="$FRAMEWORK/$FRAMEWORK_EXECUTABLE_NAME"echo "Executable is $FRAMEWORK_EXECUTABLE_PATH"

EXTRACTED_ARCHS=()

for ARCH in $ARCHS
do
echo "Extracting $ARCH from $FRAMEWORK_EXECUTABLE_NAME"
lipo -extract "$ARCH" "$FRAMEWORK_EXECUTABLE_PATH" -o
"$FRAMEWORK_EXECUTABLE_PATH-$ARCH"
EXTRACTED_ARCHS+=("$FRAMEWORK_EXECUTABLE_PATH-$ARCH")
done

echo "Merging extracted architectures: ${ARCHS}"
lipo -o "$FRAMEWORK_EXECUTABLE_PATH-merged" -create
"${EXTRACTED_ARCHS[@]}"
rm "${EXTRACTED_ARCHS[@]}"

echo "Replacing original executable with thinned version"
rm "$FRAMEWORK_EXECUTABLE_PATH"
mv "$FRAMEWORK_EXECUTABLE_PATH-merged" "$FRAMEWORK_EXECUTABLE_PATH"

done

if you encounter an error stating that there is a syntax error in the script try removing unrecognized characters that may have been copied while you were trying to copy the script
since xcode does not process them and it happened with me. So copy the code and place in a different code editor that is capable of processing such characters (visual studio for example) and then remove the unwanted characters from the end of certain lines.
So now in total you have two scripts running