C# unmanaged function pointers for iOS

Just a reminder to myself when I need this thing next time for making Unity work with native code:

• delegate method should be static to please AOT compiler required for iOS

• method should have have [MonoPInvokeCallback(typeof(YourDelegate))] attribute. its code is as simple as this:

  [AttributeUsage (AttributeTargets.Method)]
  
  public sealed class MonoPInvokeCallbackAttribute : Attribute
  
  {
  
      public MonoPInvokeCallbackAttribute (Type t) {}
  
  }

• for other platforms, delegate should have [UnmanagedFunctionPointer(YourCallingConvention)] attribute, but for iOS it prevents AOT compilation for some reason, so we need to #if it

From : http://nadako.tumblr.com/post/82111636787/c-unmanaged-function-pointers-for-ios