Can we use BWToolKit or any other IB plug-ins in Xcode 4?
My old project uses the BWToolKit and now I can't open it without Interface Builder.
Note (added Oct 26, 2011): This answer is somewhat outdated now. See comments.
Xcode 4 (as of time of this writing) does not support IBPlugins at all.
You'll need to install Xcode 3 and its Interface Builder to edit nibs with IBPlugins.
(Be careful installing Xcode3 though, as it might overwrite your Xcode4 unwantedly)
So in short: use Xcode3's IB for editing IBPlugin-infected nibs and Xcode4 for al the rest.
To my knowledge there has not been a public announcement/statement gegarding IBPlugins and whether to still stick to them, or not. ast time I checked (day after Xcode4's release) documentation on IBPlugin still existed and I couldn't find any mark on deprecation (or strangely enough not even Xcode4 incompatibilities) either.
For more info, let me quote from Martin Pilkington's great Xcode4 review:
Loss of IBPlugins:
For all the cool new hotness in Xcode 4, there is one big gaping hole in its functionality. IBPlugins cannot be loaded and as such any NIBs that rely on components from them cannot be edited. They can be compiled, but only if you have Xcode 3 and IB 3 still installed. This is a major missing component, though it isn't unexpected. A line has to be drawn at some point in order to say "this is the first version we'll ship" and IBPlugins are likely one of the things that didn't make the cut for 4.0. Of course the big issues with IBPlugins is they don't work with iOS. My hope is that they're missing because Apple is working on an improved system and would rather leave it out of 4.0 than ship a half implemented solution. That said I hope they don't completely replace the IBPlugin system as it is incredibly powerful and one of the nicest plugin systems I've coded for.
From what I've read, existing plugins won't work, or will be very unstable. The consensus on this seems to be that if you rely on plugins, stick with Xcode3 for the time being.
The folder: /Developer/Platforms/MacOSX.platform/Developer/Library/Interface Builder/Plug-ins/ has a bunch of '*.ibplugin's. Don't know what that means.
来源：https://stackoverflow.com/questions/5368878/xcode-4-and-bwtoolkit