Why do i need library file with -sources suffix?

Question

I don't understand why there are often two files in libraries, one with -sources suffix.

Here's what i mean

Answer 1

The sources are useful if you want to step into the library when debugging. You don't need them, but they might save you if you can't understand why the library behaves in a certain way.

Answer 2

要添加到下面的答案，-source存档是实际的源代码，而另一个文件是它的编译版本。