# Unity Port XNA to iOS step-by-step (using MonoGame)

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Hey everyone,

So I have an XNA 4.0 windows game in VS2010 running on my Windows PC (windows 7).

The game itself isn't finished yet, but before I continue work on it I'd like to try to get it running on my iPad, so that I suss out the porting procedure and feel confident about continuing to use XNA. The primary platforms I'd like this game to go on would be on Windows (and possibly Mac) and iOS.

I know that monogame is the way to go with porting XNA to iOS, but I'm finding it difficult finding step by step walkthroughs as to how to actually do this.

This is what I currently have:

A windows 7 PC

Visual Studio 2010

My XNA 4.0 game project on windows 7

A Macbook

MonoDevelop (it was installed as part of the Unity 4.0 install)

An iOS developer account

Latest XCode

Can anyone point me to any tutorials or guides as to how I can, from here, get my game ported over to iOS? Any comprehensive help and tips along with them would be much appreciated.

Thanks so much.

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Well... now time for the bad news...

You also need a copy of Xamarin for iOS ( previously known as MonoTouch ).

Now for the worser bad news...

Actually, no longer! If you use their brand-new Xamarin Studio package, you can release to Android, iOS, and Mac OS X for free. The free version is really only usable for smaller apps that don't require P/Invoke (its not supported) and the version that does support P/Invoke is $299 (for everything). Its not perfect, but its a good starting point. As far as XNA to MonoGame is concern, it should be pretty straight forward if you are only of Windows. When you get into Mac and Linux it does become slightly more complicated. I've never really worked with XNA or MonoGame, but people who I know have (and made the switch) say it isn't had to move. Still, my first move would be to switch from XNA to MonoGame in Windows first and then switch from Windows to Mac OS X or Linux. #### Share this post ##### Link to post ##### Share on other sites Well... now time for the bad news... You also need a copy of Xamarin for iOS ( previously known as MonoTouch ). Now for the worser bad news... It has a 299$ price tag.  There is however a 30 day full functioning trial I believe.

Actually, no longer! If you use their brand-new Xamarin Studio package, you can release to Android, iOS, and Mac OS X for free. The free version is really only usable for smaller apps that don't require P/Invoke (its not supported) and the version that does support P/Invoke is \$299 (for everything). Its not perfect, but its a good starting point.

As far as XNA to MonoGame is concern, it should be pretty straight forward if you are only of Windows. When you get into Mac and Linux it does become slightly more complicated. I've never really worked with XNA or MonoGame, but people who I know have (and made the switch) say it isn't had to move. Still, my first move would be to switch from XNA to MonoGame in Windows first and then switch from Windows to Mac OS X or Linux.

The pInvoke limitation is worse than you think...  Your code may not require pInvoke, but MonoGame does ( that's how it calls to OpenGL ).  I may be wrong, but im 90% certain the "free" version doesn't work with MonoGame.

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The pInvoke limitation is worse than you think...  Your code may not require pInvoke, but MonoGame does ( that's how it calls to OpenGL ).  I may be wrong, but im 90% certain the "free" version doesn't work with MonoGame.

Well MonoGame uses OpenTK for the OpenGL/ES backends. I checked the source code and it uses System.Runtime.InteropServices not DllImport or any of the other P/Invoke methods (although I don't know what InteropServices does in the backend).

EDIT: Information in this post is completely wrong and invalid.

Edited by Josh Vega

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Well MonoGame uses OpenTK for the OpenGL/ES backends. I checked the source code and it uses System.Runtime.InteropServices not DllImport or any of the other P/Invoke methods (although I don't know what InteropServices does in the backend).

I think you misunderstand what p/invoke means.

p/invoke is a shorthand for saying it uses InteropServices to perform automatic marshalling to and from the platform's libraries rather than using the .net method.

The source code you linked to has about 600 lines of this:

[System.Security.SuppressUnmanagedCodeSecurity()]
[System.Runtime.InteropServices.DllImport(GL.Library, EntryPoint = "glDrawArrays", ExactSpelling = true)]
internal extern static void DrawArrays(OpenTK.Graphics.ES20.BeginMode mode, Int32 first, Int32 count);
[System.Security.SuppressUnmanagedCodeSecurity()]
[System.Runtime.InteropServices.DllImport(GL.Library, EntryPoint = "glDrawElements", ExactSpelling = true)]
internal extern static void DrawElements(OpenTK.Graphics.ES20.BeginMode mode, Int32 count, OpenTK.Graphics.ES20.DrawElementsType type, IntPtr indices);



That is a textbook example of p/invoke.

You wrote it does not use DllImport, but every single one of those entries is marked as DllImport.  Every single function is marked with "System.Runtime.InteropServices.DllImport".

That is what Serapth was pointing out.  It uses p/invoke all over the place, which your source code link confirmed rather than denied.

This is one reason I personally dislike the "free" libraries that have requirements of paid libraries.  They are generally less free than they advertise.

Edited by frob

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Woah!

I don't even know how I missed that. I know that from prior experience that InteropServices is a P/Invoke method. I must have have gotten the question confused with another C# question I was emailed by a friend. Its been a busy day for me.

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@SeraPath and @Josh Vega: The MonoGame team is working with Xamarin, to have their assemblies white listed, so they can be used with the Free version.

No ETA yet, but it is coming.

@dechorus, I would suggest posting any questions you have in the monogame.codeplex.com discussion forums.

D.

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@SeraPath and @Josh Vega: The MonoGame team is working with Xamarin, to have their assemblies white listed, so they can be used with the Free version.

No ETA yet, but it is coming.

Now that is an excellent news ! Do I understand it correctly that when these assemblies are whitelisted, one will be able to use the free version of Xamarin, then ?

To be more specific, if I am not using any other assemblies (other than .NET and XNA), I read it that I actually am not doing any other PInvoke, correct ?

Or will only XNA replacements will be whitelisted, but not the .NET ones [for the free version] ?

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Unfortunately the free version of Xamarin also has a limited app size. I forget the exact size (it's hard to find on their website), but it's very tiny (I think 32KB). The default XNA project already exceeds that size because of the icon. You can shrink the icon, but any not-completely-trival game will exceed that size with just compiled code.

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32 KBs, as in, half the RAM of an 8-bit Atari 800 XL, from an era almost half a century ago ?

"But -hey- it's free !"

You gotta admit though, that's one great way how to piss potential customers.

I bet that must have been an idea of some CTO. Those are usually the ones displaced / torn out from the reality the most...

I sure would like the stuff they're smoking. Must be of top-most Columbian quality

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