What is the COMPILER_INDEX_STORE_ENABLE xcode build settings default value?

Question

There is Default, YES, NO, but what is the Default value? is YES or NO?

https://xcodebuildsettings.com/#compiler_index_store_enable

Answer 1

tl;dr: it defaults to YES.

Based on empirical observations and logical conclusions (hah), this property always defaults to YES, as of today.

This setting is what enables indexing of features such as autocompletion and rich navigation in Xcode. So when you build the project via Xcode, it will certainly be true, because it will seize the opportunity that the project is already being built to create that indexing for us.

One would expect that this property should default to NO when building via CLI (i.e. xcodebuild command line), however, as reported by Peter Stainberger here, that's not the case:

So yeah, as of today, this always defaults to YES, however, it could be changed in the future.