Question

I created a static cocos project in xcode, the entire project consisted of a single .c file called File.c and this function:

   int Get10()
   {
       return 10;
   }

I created a target for it called ‘Numbers’ and built the project, which created a libNumbers.a. I moved libNumbers.a to my MonoTouch projects root directory and in the additional mtouch arguments area I added:

-gcc_flags “-L${ProjectDir} -lNumbers -force_load
${ProjectDir}/libNumbers.a”

The code compiled fine.

So in a C# file in my MonoTouch project I added the following:

    [DllImport ("libNumbers.a")]
    private static extern int Get10 ();

(I’ve also tried doing [DllImport (“Numbers.a”)])

Then during exception a function called Get10(). This throws the following exception:

System.DllNotFoundException: libNumbers.a at (wrapper
managed-to-native) Jabber.BaseGame:Get10 () at Jabber.BaseGame.Draw
(Microsoft.Xna.Framework.GameTime dt) [0x00043] in
/Users/ahmedhakeem/Documents/Projects/goodjabberengine/MyCode/Engine/BaseGame.cs:103

From what I can see it looks like it’s unable to find the dll in question.

One possible cause is that I call the function Get10 (and import it) to a source file in a seperate library project (i.e. not the project I added the additional mtouch arguments). There is no way of adding mtouch arguments to a library project in monotouch which you’re linking in so I don’t think that’s an option.

So any ideas on how to fix this?

Answer 1

If the library is linked with the app when the symbols becomes internal (inside the main app). In this case the correct declaration will be:

[DllImport ("__Internal")]
extern static void YourLinkedNativeCode ();