Question

NOTE: Perhaps this question could be answered by a pure Objective-C expert as well? I work primarily in MonoTouch, but I think this problem may not be MonoTouch-specific.

Typically when the Assistant Editor in XCode won’t show my .h file, I just close everything, delete my obj directory, and rebuild all. I wait for the Indexing process to complete. But this time I really can’t get the .h file to show up, and thus I’m unable to add any new outlets to my FooViewController.

So far, I’ve tracked it down to an empty IBClassDescriber element in my FooViewController.xib

<object class="IBClassDescriber" key="IBDocument.Classes"/>

which should look something more like:

<object class="IBClassDescriber" key="IBDocument.Classes">
        <array class="NSMutableArray" key="referencedPartialClassDescriptions">
                <object class="IBPartialClassDescription">
                        <string key="className">FooViewController</string>
                        <string key="superclassName">UIViewController</string>
                        <dictionary class="NSMutableDictionary" key="outlets">
                            ...
                        </dictionary>
                        <dictionary class="NSMutableDictionary" key="toOneOutletInfosByName">
                            ...
                        </dictionary>
                        <object class="IBClassDescriptionSource" key="sourceIdentifier">
                                <string key="majorKey">IBProjectSource</string>
                                <string key="minorKey">./Classes/FooViewController.h</string>
                        </object>
                </object>
        </array>
</object>

which has the link to the .h file in the minorKey of IBClassDescriptionSource.

I’ve tried cleaning my project, closing all my apps and deleting the obj and bin directories. I’ve tried renaming the file (along with the above). And other various sporadic cursing and deleting/reverting/and banging things loudly. To no avail.

Anyone know how to recover the IBClassDescriber element once it’s been emptied?

I’m going to have a look back through the file history and see when it disappeared. Maybe that’ll give me a clue.

Thanks!
CM

Answer 1

So this scenario came about (like other people have done) when I had renamed my ViewController file and failed to update all references to the old name. There are several places the name of the view controller needs to change, but there are really only 2 critical places that need to match to get XCode and MonoDevelop in synch. For this example, assume I had a view controller named FooViewController and had renamed it to BarViewController.

First, every time you launch XCode (XC), MonoDevelop (MD) creates a temporary directory named obj/XCode/# where # starts at 0 and increments by one every time you re-launch XC. The number resets to 0 every time you restart MD. Every time you close XC and return to MD, the directory will be deleted.

NOTE: the directory will NOT be deleted if you are browsing the directory from Finder or Terminal, etc.

MD creates the required .h and .m files in that directory that XC expects to see. The names of these files are based on the value if the Register attribute in YourViewController.designer.cs. In my case, I had properly updated the .designer file to:

[Register ("BarViewController")]

Now when I open the .xib I get the dreaded No Assistant Results error.

At this point, my .xib file, when opened in the Source Code Editor of MD, showed a full IBClassDescriber section (though improperly referencing ./Classes/FooViewController.h since I hadn’t updated it yet).

What I did next was to save the .xib from XC. Since XC could not find ./Classes/FooViewController.h (MD was now generating BarViewController.h), it deleted the IBClassDescriber section from the .xib, giving me an empty entity

<object class="IBClassDescriber" key="IBDocument.Classes"/>

I had failed to update the .xib properly, now I had lost this entire section (which had numerous references that I didn’t want or know how to recreate).

The key to fixing this was noticing that the -1.CustomClassname property in the .xib was set incorrectly. Updating it to match the Register setting

<dictionary class="NSMutableDictionary" key="flattenedProperties">
    <string key="-1.CustomClassName">BarViewController</string>
    ...
</dictionary>

and re-saving the file resulted in XC recreating the entire IBClassDescriber section with proper references to the .h file

<object class="IBClassDescriber" key="IBDocument.Classes">
        <array class="NSMutableArray" key="referencedPartialClassDescriptions">
                <object class="IBPartialClassDescription">
                        <string key="className">BarViewController</string>
                        <string key="superclassName">UIViewController</string>
                        <object class="NSMutableDictionary" key="outlets">
                            ...
                        </object>
                        <object class="NSMutableDictionary" key="toOneOutletInfosByName">
                            ...
                        </object>
                        <object class="IBClassDescriptionSource" key="sourceIdentifier">
                                <string key="majorKey">IBProjectSource</string>
                                <string key="minorKey">./Classes/BarViewController.h</string>
                        </object>
                </object>
        </array>
</object>

So in summary, when you’re renaming files, the places to change are:

1. Refactor/Rename your main ViewController class (e.g. FooViewController.cs to BarViewControllercs. Using Refactor (right click class file -> refactor -> rename) will update lots of stuff for you, including the .designer file and any references to the class throughout your code
2. Change the string value passed to the superclass in your ViewController constructor public GrepViewController () : base ("BarViewController", null) which is required for loading the class at runtime
3. Open your .designer file and change the Register call so that the link between XC and MD is maintained: [Register ("BarViewController")] partial class BarViewController
4. Rename the .xib: BarViewController.xib
5. Open BarViewController.xib in MD with source editor (right click -> open with -> Source Code Editor) and change the -1.CustomClassName key: <string key="-1.CustomClassName">BarViewController</string>
6. Save the .xib from MD
7. Open BarViewController.xib in XC. (If you’ve got it open in MD, you’ll need to right click -> Open With -> XCode). Wait for indexing to complete, then open the Assistant Editor. Notice that BarViewController.h is (correctly) opened.
8. Save the .xib from XC.
9. Open the .xib in MD and notice that IBClassDescriber section is fully specified, even if it was empty to start with.

Ship it!

Hope this helps someone, clears up some mystery of the linkage between XC and MD, or at least reminds me what to do next time I run into this problem.

Cheers,
CM