Object Oriented bridging through C

1-MyClass.mm

#import <Foundation/Foundation.h>

typedef NS_ENUM(NSUInteger, BatteryStatus)
{
	BatteryStatusUnknown,
	BatteryStatusOkay,
	BatteryStatusLow,
	BatteryStatusEmpty
};

@protocol MyClassDelegate <NSObject>

@optional

- (void)batteryStatusDidChange:(BatteryStatus)status;

@required

- (void)audioWasPaused;
- (void)audioWasResumed;

@end

@interface MyClass : NSObject

- (NSString *)doSomething;
- (void)somethingElse:(int)number;
- (void)start:(void (^)(BOOL success))completion;

@property (nonatomic, weak) id <MyClassDelegate> delegate;
@property (nonatomic, assign) int myNumber;
@property (nonatomic, strong) NSString *myString;

@end

/////

typedef void (*MyClass_completionDelegate)(BOOL success);

typedef void (*MyClassDelegate_batteryStatusDidChangeDelegate)(BatteryStatus status);
typedef void (*MyClassDelegate_audioWasPausedDelegate)();
typedef void (*MyClassDelegate_audioWasResumedDelegate)();

@interface MyClassDelegateBridge : NSObject <MyClassDelegate>

@property (nonatomic, assign) MyClassDelegate_batteryStatusDidChangeDelegate batteryStatusDidChangeCallback;
@property (nonatomic, assign) MyClassDelegate_audioWasPausedDelegate audioWasPausedCallback;
@property (nonatomic, assign) MyClassDelegate_audioWasResumedDelegate audioWasResumedCallback;

@end

#if __cplusplus
extern "C" {
#endif

	extern void *MyClass_init();
	extern char *MyClass_doSomething(void *instance);
	extern void MyClass_somethingElse(void *instance, int number);
	extern void MyClass_start(void *instance, MyClass_completionDelegate completion);
	extern void *MyClass_delegate(void *instance);
	extern void MyClass_setDelegate(void *instance, void *value);
	extern int MyClass_myNumber(void *instance);
	extern void MyClass_setMyNumber(void *instance, int value);
	extern char *MyClass_myString(void *instance);
	extern void MyClass_setMyString(void *instance, char *value);

	extern void *MyClassDelegate_init();
	extern MyClassDelegate_batteryStatusDidChangeDelegate MyClassDelegate_batteryStatusDidChangeCallback(void *instance);
	extern void MyClassDelegate_setBatteryStatusDidChangeCallback(void *instance, MyClassDelegate_batteryStatusDidChangeDelegate value);
	extern MyClassDelegate_audioWasPausedDelegate MyClassDelegate_audioWasPausedCallback(void *instance);
	extern void MyClassDelegate_setAudioWasPausedCallback(void *instance, MyClassDelegate_audioWasPausedDelegate value);
	extern MyClassDelegate_audioWasResumedDelegate MyClassDelegate_audioWasResumedCallback(void *instance);
	extern void MyClassDelegate_setAudioWasResumedCallback(void *instance, MyClassDelegate_audioWasResumedDelegate value);

#if __cplusplus
}
#endif

2-MyClass.cs

using System;
using System.Runtime.InteropServices;

public enum BatteryStatus : int
{
	Unknown,
	Okay,
	Low,
	Empty
}

public class MyClassDelegate
{
	public delegate void BatteryStatusDidChangeDelegate(BatteryStatus status);
	public delegate void AudioWasPausedDelegate();
	public delegate void AudioWasResumedDelegate();

	private static class C
	{
		[DllImport("__Internal", EntryPoint="MyClassDelegate_init")]
		public static extern IntPtr init();

		[DllImport("__Internal", EntryPoint="MyClassDelegate_batteryStatusDidChangeCallback")]
		public static extern BatteryStatusDidChangeDelegate batteryStatusDidChange(IntPtr instance);

		[DllImport("__Internal", EntryPoint="MyClassDelegate_setBatteryStatusDidChangeCallback")]
		public static extern void setBatteryStatusDidChange(IntPtr instance, BatteryStatusDidChangeDelegate value);

		[DllImport("__Internal", EntryPoint="MyClassDelegate_audioWasPausedCallback")]
		public static extern AudioWasPausedDelegate audioWasPaused(IntPtr instance);

		[DllImport("__Internal", EntryPoint="MyClassDelegate_setAudioWasPausedCallback")]
		public static extern void setAudioWasPaused(IntPtr instance, AudioWasPausedDelegate value);

		[DllImport("__Internal", EntryPoint="MyClassDelegate_audioWasResumedCallback")]
		public static extern AudioWasResumedDelegate audioWasResumed(IntPtr instance);

		[DllImport("__Internal", EntryPoint="MyClassDelegate_setAudioWasResumedCallback")]
		public static extern void setAudioWasResumed(IntPtr instance, AudioWasResumedDelegate value);
	}

	public readonly IntPtr _instance;

	public MyClassDelegate()
	{
		_instance = C.init();
	}

	public MyClassDelegate(IntPtr instance)
	{
		_instance = instance;
	}

	public BatteryStatusDidChangeDelegate BatteryStatusDidChange
	{
		get { return C.batteryStatusDidChange(_instance); }
		set { C.setBatteryStatusDidChange(_instance, value); }
	}

	public AudioWasPausedDelegate AudioWasPaused
	{
		get { return C.audioWasPaused(_instance); }
		set { C.setAudioWasPaused(_instance, value); }
	}

	public AudioWasResumedDelegate AudioWasResumed
	{
		get { return C.audioWasResumed(_instance); }
		set { C.setAudioWasResumed(_instance, value); }
	}
}

public class MyClass
{
	public delegate void CompletionDelegate(bool success);

	private static class C
	{
		[DllImport("__Internal", EntryPoint="MyClass_init")]
		public static extern IntPtr init();

		[DllImport("__Internal", EntryPoint="MyClass_doSomething")]
		public static extern string doSomething(IntPtr instance);

		[DllImport("__Internal", EntryPoint="MyClass_somethingElse")]
		public static extern void somethingElse(IntPtr instance, int number);

		[DllImport("__Internal", EntryPoint="MyClass_start")]
		public static extern void start(IntPtr instance, CompletionDelegate completion);

		[DllImport("__Internal", EntryPoint="MyClass_delegate")]
		public static extern IntPtr @delegate(IntPtr instance);

		[DllImport("__Internal", EntryPoint="MyClass_setDelegate")]
		public static extern void setDelegate(IntPtr instance, IntPtr value);

		[DllImport("__Internal", EntryPoint="MyClass_myNumber")]
		public static extern int myNumber(IntPtr instance);

		[DllImport("__Internal", EntryPoint="MyClass_setMyNumber")]
		public static extern void setMyNumber(IntPtr instance, int value);

		[DllImport("__Internal", EntryPoint="MyClass_myString")]
		public static extern string myString(IntPtr instance);

		[DllImport("__Internal", EntryPoint="MyClass_setMyString")]
		public static extern void setMyString(IntPtr instance, string value);
	}

	public readonly IntPtr _instance;

	public MyClass()
	{
		_instance = C.init();
	}

	public MyClass(IntPtr instance)
	{
		_instance = instance;
	}

	public string DoSomething()
	{
		return C.doSomething(_instance);
	}

	public void SomethingElse(int number)
	{
		C.somethingElse(_instance, number);
	}

	public void Start(CompletionDelegate completion)
	{
		C.start(_instance, completion);
	}

	public MyClassDelegate Delegate
	{
		get { return new MyClassDelegate(C.@delegate(_instance)); }
		set { C.setDelegate(_instance, value._instance); }
	}

	public int MyNumber
	{
		get { return C.myNumber(_instance); }
		set { C.setMyNumber(_instance, value); }
	}

	public string MyString
	{
		get { return C.myString(_instance); }
		set { C.setMyString(_instance, value); }
	}
}