libs-uikit

libs-uikit is a GNUstep Objective-C library that provides a UIKit-like API on top of GNUstep Base and GUI. It is intended for code that wants familiar UIKit class names and application structure while running in a GNUstep/AppKit environment.

The library currently exposes a focused subset of UIKit-style classes including application/window management, views and view controllers, common controls, table/navigation/tab containers, images, colors, fonts, nib loading helpers, and basic device/screen abstractions.

This is currently a POC which may have significant gaps with the actual UIKit. It illustrates that using AppKit to create some of the widgets needed for UIKit is possible.

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 the UIKitExample application.

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.

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");
}

The public API is intentionally modeled around UIKit names, but the underlying types are GNUstep/AppKit types. For example, CGPoint, CGSize, and CGRect are typedefs for NSPoint, NSSize, and NSRect.

Implemented Public Headers

• UIApplication, UIResponder, UIScreen, UIDevice
• UIView, UIWindow, UIViewController
• UIColor, UIImage, UIFont
• UILabel, UIImageView
• UIControl, UIButton, UITextField, UITextView
• UISlider, UISwitch, UISegmentedControl, UIScrollView
• UITableView, UITableViewCell, NSIndexPath+UIKit
• 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.