Objective-C for Unity

High level C# to Objective-C interface, similar to Unity's AndroidJavaClass and AndroidJavaObject.

WARNING: this is highly experimental and unsafe, misusage may easily crash the Unity editor or built games! Use at your own risk.

Note: You have to manage memory on your own, since Automatic Reference Couting (ARC) in Objective-C is a compiler feature and we are not calling the compiler here. This plugin offers some IDisposable structures to facilitate this, like StrongReference (calls Release when disposed) and DisposablePinnedObject (pins objects with GCHandle, calls Free on the handle when disposed). You are responsible for releasing objects you own, as well as knowing which objects are autoreleased and should not be released again.

Samples

This UPM package has 2 samples:

• macOS NSAlert: Sample code that presents a native macOS alert
• iOS UIFeedbackGenerator: Sample code that plays haptics using UIImpactFeedbackGenerator on iOS

Usage example

#if UNITY_EDITOR_OSX || UNITY_STANDALONE_OSX  // || UNITY_IOS (NSAlert is not support in iOS)
using System;
using Gilzoide.ObjectiveC;
using Gilzoide.ObjectiveC.Foundation;
using UnityEngine;

public static class NSAlertMessage
{
  private static Action<Id> _onAlertDismissedAction;

  public static void Alert(string message)
  {
    // Get existing Objective-C classes using `new Class("...")`
    Class NSApplication = new Class("NSApplication");
    // Use `Call` to send messages to an Id or Class using selectors
    // Selectors must match exactly with the definition, including the `:` characters
    // When returning values, you MUST pass a type with the right size or the application may crash
    // `Id` is like Objective-C's `id` type, a dynamic object that can receive messages
    Id sharedApplication = NSApplication.Call<Id>("sharedApplication");
    // `Get` is just a wrapper over `Call` for the getter selector
    Id keyWindow = sharedApplication.Get<Id>("keyWindow");

    Class NSAlert = new Class("NSAlert");
    // Instantiate objects with `Alloc(initSelector)` (in Objective-C idiom: `[[Class alloc] init]`)
    // The return is a StrongReference, a disposable version of `Id` that calls `Release` on Dispose
    using (StrongReference alert = NSAlert.Alloc("init"))
    {
      // Constructors for basic Foundation classes (currently NSString and NSNumber) are available
      // `+ [NSString stringWith*]` methods return an autoreleased NSString, no need to `Release`
      AutoreleasedReference<NSString> objcMessage = NSString.StringWith(message);

      // `Set` is just a wrapper over `Call` for the setter selector
      alert.Set("messageText", objcMessage);

      // Create Objective-C blocks from C# Delegates using `Block.FromDelegate`
      // Delegates MUST receive the block as first parameter (e.g. with `Id` type), as per block ABI
      // You are responsible for maintaining the Delegate alive when the block is called
      // The simplest way is to maintain the Delegate in a static or instance field
      _onAlertDismissedAction = _block => Debug.Log($"Alerted with message: '{message}'");
      Block block = Block.FromDelegate(_onAlertDismissedAction);
      // Blocks are passed by reference in Objective-C, so we need to get its address first
      // `DisposablePinnedObject` is a disposable wrapper over `GCHandle`
      using (DisposablePinnedObject pinnedBlock = new DisposablePinnedObject(block))
      {
        IntPtr blockByReference = pinnedBlock.Address;

        // You can pass any number of struct values as parameters
        alert.Call("beginSheetModalForWindow:completionHandler:", keyWindow, blockByReference);
      }
    }
  }
}
#endif