Question

I’ve not found anything that addresses my specific name space question as yet.

I am working on some AudioUnit plug-ins featuring Cocoa based GUIs. The plug-ins use a common library of user interface classes (sliders, buttons etc) which are simply added to each Xcode project.

When I recompile and distribute updates it is pretty much guaranteed that at least one user interface class will have been updated since the last release. If the user launches an older plug-in before an updated plug-in then the old Cocoa classes are already loaded into the run time and the plug-in attempts to use the older implementations – often resulting in a failure one way or another.

I know frameworks are the intended solution but the overhead and backwards compatibility issues are not ideal. I prefix all class names where possible but what options do I have to ensure that each plug-in contains unique class names for the shared user interface classes?

Update:

The solution I seem to be arriving at is as follows:

1. Set a preprocessor compiler flag e.g. OBJC_PREFIX=1.

2. Create a header file to contain all the class name redefinitions and conditionally include it in the header of each class you want to ‘rename’ e.g:

   #ifdef OBJC_PREFIX  
   #include "CocoaPrefixHeader.h"  
   #endif  
   @interface MySlider : ... etc
   

3. Fill the header file (in this case CocoaPrefixHeader) with something like the following:

   #define MySlider Prefix_MySlider  
   #define MyButton Prefix_MyButton  
   

4. Using ibtool convert all your class names in an existing nib/xib file to the new names e.g:

   ibtool --convert MySlider-Prefix_MySlider nibfile.xib --write nibfile2.xib  
   ibtool --convert MyButton-Prefix_MyButton nibfile2.xib --write nibfile2.xib
   

This last step converts all class names and outlets etc in the nib file. Once converted you can edit the nib as normal and IB keeps track of the redefined names.

This process is tedious and laborious but it is working for me. Far better to cater for it at the outset.

Answer 1

Whilst the solution I arrived at in the updated part of the question works as the final step in a project I can’t recommend it for anything where your classes are in a state of flux. I was unable to add additional outlets to classes and have them show up in IB, for example.

In the end I just duplicated my classes and added unique name prefixes for different projects. Using ibtool –convert to update the xib file made this process a lot faster.

Once things settle down maybe a framework will be a better idea.