Build a minimal unsigned iOS IPA with CMake and Ninja that includes a raw arm64 Mach-O .so in Frameworks/, loads it at launch, and crashes if loading fails.

build_ipa.sh

#!/bin/bash
# Build an unsigned arm64 iOS IPA containing an iOS shared library named .so.
# Requirements: macOS, Xcode with the iOS SDK, CMake >= 3.24, and Ninja.
set -euo pipefail

script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
cd "$script_dir"

for tool in cmake ninja xcrun zip; do
    command -v "$tool" >/dev/null 2>&1 || {
        echo "Missing required tool: $tool" >&2
        exit 1
    }
done
[ "$(uname -s)" = Darwin ] || { echo "Run this script on macOS with Xcode installed." >&2; exit 1; }

source_dir="$script_dir/build/ios-source"
build_dir="$script_dir/build/standalone-ios"
mkdir -p "$source_dir/src" "$build_dir"

# Keep the example project inside this script so it is the only source file needed.
cat > "$source_dir/CMakeLists.txt" <<'CMAKE'
cmake_minimum_required(VERSION 3.24)
project(SoDemo LANGUAGES C OBJC)

if(NOT CMAKE_SYSTEM_NAME STREQUAL "iOS")
    message(FATAL_ERROR "Configure this project for iOS.")
endif()

# Emit a raw Mach-O plugin, matching the .so entries in the reference IPA.
add_library(demo_library MODULE src/demo_library.c)
set_target_properties(demo_library PROPERTIES
    PREFIX ""
    OUTPUT_NAME "demo_library"
    SUFFIX ".so"
)

add_executable(SoDemo MACOSX_BUNDLE src/main.m)
set_target_properties(SoDemo PROPERTIES
    MACOSX_BUNDLE_INFO_PLIST "${CMAKE_CURRENT_SOURCE_DIR}/src/Info.plist.in"
    MACOSX_BUNDLE_GUI_IDENTIFIER "com.example.sodemo"
)
target_compile_options(SoDemo PRIVATE -fobjc-arc)
target_link_libraries(SoDemo PRIVATE "-framework UIKit" "-framework Foundation")

# Produce an unsigned IPA for later signing/sideloading.
target_link_options(demo_library PRIVATE "LINKER:-no_adhoc_codesign")
target_link_options(SoDemo PRIVATE "LINKER:-no_adhoc_codesign")

# Copy the unsigned plugin beside other app resources, as in the reference IPA.
add_custom_target(embed_library ALL
    COMMAND ${CMAKE_COMMAND} -E make_directory
        "$<TARGET_BUNDLE_DIR:SoDemo>/Frameworks"
    COMMAND ${CMAKE_COMMAND} -E copy
        "$<TARGET_FILE:demo_library>"
        "$<TARGET_BUNDLE_DIR:SoDemo>/Frameworks/demo_library.so"
    DEPENDS SoDemo demo_library
    VERBATIM
)
CMAKE

cat > "$source_dir/src/demo_library.c" <<'C'
const char *demo_message(void)
{
    return "Hello from the .so library!";
}
C

cat > "$source_dir/src/Info.plist.in" <<'PLIST'
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>CFBundleDevelopmentRegion</key><string>en</string>
    <key>CFBundleDisplayName</key><string>SO Demo</string>
    <key>CFBundleExecutable</key><string>SoDemo</string>
    <key>CFBundleIdentifier</key><string>com.example.sodemo</string>
    <key>CFBundleInfoDictionaryVersion</key><string>6.0</string>
    <key>CFBundleName</key><string>SoDemo</string>
    <key>CFBundlePackageType</key><string>APPL</string>
    <key>CFBundleShortVersionString</key><string>1.0</string>
    <key>CFBundleVersion</key><string>1</string>
    <key>CFBundleSupportedPlatforms</key><array><string>iPhoneOS</string></array>
    <key>MinimumOSVersion</key><string>15.0</string>
    <key>UIDeviceFamily</key><array><integer>1</integer><integer>2</integer></array>
    <key>LSRequiresIPhoneOS</key><true/>
    <key>UILaunchScreen</key><dict/>
    <key>UIApplicationSceneManifest</key>
    <dict>
        <key>UIApplicationSupportsMultipleScenes</key><false/>
        <key>UISceneConfigurations</key>
        <dict>
            <key>UIWindowSceneSessionRoleApplication</key>
            <array><dict>
                <key>UISceneConfigurationName</key><string>Default</string>
                <key>UISceneDelegateClassName</key><string>SceneDelegate</string>
            </dict></array>
        </dict>
    </dict>
</dict>
</plist>
PLIST

cat > "$source_dir/src/main.m" <<'OBJC'
#import <UIKit/UIKit.h>
#include <dlfcn.h>

static NSString *loadMessage(void)
{
    NSString *path = [NSBundle.mainBundle.privateFrameworksPath
        stringByAppendingPathComponent:@"demo_library.so"];
    void *library = dlopen(path.fileSystemRepresentation, RTLD_NOW);
    if (!library) {
        NSLog(@"dlopen failed: %s", dlerror());
        abort();
    }

    dlerror();
    const char *(*message)(void) = (const char *(*)(void))dlsym(library, "demo_message");
    const char *error = dlerror();
    if (error || !message) {
        NSLog(@"demo_message lookup failed: %s", error ? error : "symbol is null");
        dlclose(library);
        abort();
    }

    NSString *result = [NSString stringWithUTF8String:message()];
    dlclose(library);
    return result;
}

@interface SceneDelegate : UIResponder <UIWindowSceneDelegate>
@property(nonatomic, strong) UIWindow *window;
@end

@implementation SceneDelegate
- (void)scene:(UIScene *)scene
    willConnectToSession:(UISceneSession *)session
    options:(UISceneConnectionOptions *)options
{
    self.window = [[UIWindow alloc] initWithWindowScene:(UIWindowScene *)scene];
    UIViewController *controller = [[UIViewController alloc] init];
    controller.view.backgroundColor = UIColor.systemBackgroundColor;
    UILabel *label = [[UILabel alloc] initWithFrame:controller.view.bounds];
    label.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    label.textAlignment = NSTextAlignmentCenter;
    label.numberOfLines = 0;
    label.text = loadMessage();
    [controller.view addSubview:label];
    self.window.rootViewController = controller;
    [self.window makeKeyAndVisible];
}
@end

@interface AppDelegate : UIResponder <UIApplicationDelegate>
@end
@implementation AppDelegate
@end

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass(AppDelegate.class));
    }
}
OBJC

cmake -S "$source_dir" -B "$build_dir" -G Ninja \
    -DCMAKE_SYSTEM_NAME=iOS \
    -DCMAKE_OSX_SYSROOT=iphoneos \
    -DCMAKE_OSX_ARCHITECTURES=arm64 \
    -DCMAKE_OSX_DEPLOYMENT_TARGET=15.0 \
    -DCMAKE_TRY_COMPILE_TARGET_TYPE=STATIC_LIBRARY \
    -DCMAKE_BUILD_TYPE=Release
cmake -E rm -rf "$build_dir/SoDemo.app/Frameworks"
cmake --build "$build_dir"

app="$build_dir/SoDemo.app"
library="$app/Frameworks/demo_library.so"
cp "$source_dir/src/Info.plist.in" "$app/Info.plist"
[ -f "$app/SoDemo" ] && [ -f "$library" ] || {
    echo "Build did not produce the app and embedded .so library." >&2
    exit 1
}

package_root="$(mktemp -d "$build_dir/package.XXXXXX")"
trap 'rm -rf -- "$package_root"' EXIT
mkdir -p "$package_root/Payload"
cp -R "$app" "$package_root/Payload/"
(cd "$package_root" && zip -qry SoDemo-unsigned.ipa Payload)
mv "$package_root/SoDemo-unsigned.ipa" "$build_dir/SoDemo-unsigned.ipa"

# Keep just the deliverables after the IPA is safely written. The standalone
# library stays beside it; app bundles, Ninja state, generated sources, and
# outputs from the earlier framework build are disposable.
find "$build_dir" -mindepth 1 -maxdepth 1 \
    ! -name SoDemo-unsigned.ipa ! -name demo_library.so \
    -exec /bin/rm -rf {} +
find "$script_dir/build" -mindepth 1 -maxdepth 1 ! -name standalone-ios \
    -exec /bin/rm -rf {} +
/bin/rm -rf "$script_dir/dist"

echo "Created unsigned IPA: $build_dir/SoDemo-unsigned.ipa"