Xcode: clean build for cordova?

I have a working cordova (phone app) build that I want to build for ios. I'm using Xcode Version 7.2.1 (7C1002).

The app built successfully, but when it runs, the screen turns white for about 30 seconds, then there's a break in malloc with a null pointer, and the memory meter indicates about 3.2 GB in use. I set a breakpoint at the first line of js for my home page (index.html), but it never gets there, just runs the memory dry first.

So I'm taking a different tack, using cordova's "workshop" project. This builds and runs ok. However, if I replace the original index.html and js/index.js with my code, it also runs ok, but acts as if it's running from the original code. Running Product/Clean and Product/Build doesn't change this, nor does Product/CleanBuildFolder and Product/Build. However, if I run "cordova platform rm ios" followed by "cordova platform add ios" (a crude manual clean on the build tree) and then run ProductBuild, it does run my code, including running out of memory before reaching the first line of my code.

I could use this approach for each line of code difference that I need to investigate between my code and the workshop sample, but it's going to be incredibly slow and boring.

So the question is: is there a way to get Xcode to really run something like a make-clean on the build tree?

Corollary: is there a way to get Xcode to build changes in a given file (e.g., index.js) without having to run a clean first?