In Objective-C, importing same headers in every class make compile time longer?

Question

I\'m a beginner of Objective-C/iOS programing.

I want make a one header file which includes all class headers I use in my project.
And import the header in every

Answer 1

In general, newly-generated iOS projects come with this functionality, which is called a precompiled header or prefix header, and is a file that has the extension .pch.

You can throw all the headers you want in there and Xcode will pre-compile it before it builds anything else, and use it to compile the other compilation units in your project (e.g. .m files).

Using a precompiled header may or may not increase compile time; in general, it reduces compile time, as long as you have a lot of common headers and/or a lot of source files.

However, it's not necessarily good practice to treat the pre-compiled header like a big dumping ground, as your compilation units can form implicit dependencies on all sorts of stuff when you may want to enforce loose coupling between components.