Using Android Studio 1.3.2, the .idea/codeStyleSettings.xml is constantly modified to add a section for
Ran into this exact problem, which hampered process since codeStyleSettings.xml was a version controlled file. Solved it (on my Windows machine if that makes a difference) with the low-tech solution of marking the file as read only. Android Studio complained about it the first time after making that change, but I prevented it from unsetting read-only and things worked fine after that.
The <Objective-C-extensions>
Section is added by the Android NDK Support Plugin. Which was added in 1.3 and is activated by default.
If you have activated this plugin it adds the Section to your codeStyleSettings.xml. Otherwise it will be removed.