Purpose of PCH file in Xcode? | iOS Interview Question | iOS Programmer Guide

.pch file is a prefix header file which is automatically created by xcode.

It is compiled and stored in cache, and automatically included in every source file during the compilation time. 


Note: Precompiling the prefix header will be most effective if the contents of the prefix header or any file it includes change rarely. If the contents of the prefix header or any file it includes change frequently, there may be a negative impact to overall build time.