Whenever I build with script debugging on, I cannot build for ios. I get the following in XCode:
ld: Unable to insert branch island. No insertion point available. for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)
I am able to compile and run otherwise without issue. Any ideas as to what might be the cause?
same problem here 
So I guess its just broken?
Find answer from this link
http://docs.unity3d.com/Documentation/printable.html
Simply they saying, reduce some codes for debugging in XCode.
Absolutely, this is a DLL size problem, you can’t exceed a certain amount (approximately 40mb).
I had a similar problem reported in this thread : http://forum.unity3d.com/threads/158335-Mach-O-linker-error-can-t-wrap-my-head-around
We’re currently facing the same problem, but achieved to get the .o files down to 35MB and still getting this “unable to insert branch island” linking error.
On another project its working well with an .o file of about 25MB. So the limit must be somewhere in between them, if it really is a file size limit and not a different kind of limit.
Anyway, this issue just sux.