libs-uikit

libs-uikit implements a growing Objective-C UIKit compatibility layer on GNUstep. The target is zero application source changes: compatibility work belongs in this framework and its build/resource tooling. Applications must be rebuilt for the target platform; this is not an iOS binary loader.

The 0.2 development version separates UIKit objects from private AppKit peers. UIResponder inherits NSObject, UIView inherits UIResponder, and UIWindow inherits UIView. Ordinary applications import <UIKit/UIKit.h> without AppKit. The supported implementation is still a subset; arbitrary iPhone applications cannot yet be expected to run unchanged. See the compatibility contract and remaining gates and tested coverage.

AI Disclosure

AI was used for some of the concepts of this library. Particularly the repetative coding parts.

Contents

• Headers/UIKit/ - public headers and the umbrella UIKit.h header.
• Source/ - Objective-C implementation files and the library makefile.
• Examples/ - a small UIKitExample GNUstep application using a xib file.
• COPYING.LIB - GNU Lesser General Public License text.

Requirements

• GNUstep Make
• GNUstep Base
• GNUstep GUI
• Objective-C compiler supported by GNUstep

GNUSTEP_MAKEFILES must be available. If it is not already exported by your environment, the top-level makefile tries to discover it with:

gnustep-config --variable=GNUSTEP_MAKEFILES

Building

From the repository root:

make

The top-level build includes both subprojects:

• Source builds the libs-uikit shared library.
• Examples builds UIKitExample, UIKitCoreCatalog, and UIKitStudio. The OpenGL example is opt-in with UIKIT_BUILD_OPENGL_EXAMPLE=yes.

To build only the library:

make -C Source

To build only the example application:

make -C Examples

Building For Android

The Android build uses the NDK CMake toolchain and builds the library target only. It expects GNUstep Base, GNUstep GUI, and libobjc to already be built for the same Android ABI and available in one prefix.

cmake -S . -B build-android \
  -DCMAKE_TOOLCHAIN_FILE="$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake" \
  -DANDROID_ABI=arm64-v8a \
  -DANDROID_PLATFORM=android-24 \
  -DGNUSTEP_ANDROID_ROOT=/path/to/android-gnustep-prefix

cmake --build build-android

GNUSTEP_ANDROID_ROOT should contain GNUstep headers under either include/GNUstep or include, and Android ABI libraries under either lib or lib/<abi>. If your Objective-C runtime is not libobjc2's GNUstep 2.0 runtime, override UIKIT_ANDROID_OBJC_RUNTIME.

Shared-source graphical demo

UIKit Studio provides an interactive editor, reusable list, and color gallery. Its application files compile unchanged against Apple UIKit for the iOS Simulator and this GNUstep implementation. Open Examples/UIKitStudio/UIKitStudio.xcodeproj in Xcode, or build the UIKitStudio target with GNUmake/CMake. The example includes a simulator launch script and shared interaction smoke checks.

Running The Example

After building, run the example application from the Examples directory using the normal GNUstep application launch method for your environment. The example creates a UIWindow, loads MainView.xib through an ExampleViewController, and demonstrates labels, text fields, sliders, switches, buttons, and control events.

Using The Library

Import the umbrella header:

#import <UIKit/UIKit.h>

Applications use the familiar UIKit-style entry point:

int main(int argc, char **argv)
{
  return UIApplicationMain(argc, argv, nil, @"ExampleAppDelegate");
}

Geometry currently uses GNUstep Foundation types. For example, CGPoint, CGSize, and CGRect are typedefs for NSPoint, NSSize, and NSRect.

Implemented Public Headers

• UIApplication, UIResponder, UIScreen, UIDevice
• UIView, UIWindow, UIViewController
• Constraint layout anchors, NSLayoutConstraint, UILayoutGuide (partial; see UIKit-Gaps.md)
• UIColor, UIImage, UIFont
• UILabel, UIImageView
• UIControl, UIButton, UITextField, UITextView
• UISlider, UISwitch, UISegmentedControl, UIScrollView
• UITableView, UITableViewCell, UITableViewController, NSIndexPath+UIKit
• UICollectionView, flow layout, cells, and UICollectionViewController
• UINavigationItem, UINavigationController, UITabBarController
• UIActivityIndicatorView, UIAlertView
• UINib, NSBundle+UIKit

License

This project is distributed under the GNU Lesser General Public License. See COPYING.LIB for the full license text.

Core tests and catalog

See RELEASE-MILESTONE-1.md for the coverage matrix. With a configured GNUstep environment, make test runs the regression suite. For a headless Linux run use xvfb-run -a make test. A CMake build also provides UIKitCoreCatalog and two CTest entries, including a catalog smoke test.