Question

When I used Xcode to debug my iOS program, gdb displayed it on console view, and no error did occur.

I just want to know the specific meaning of the output “Current language: auto; currently objective-c”.

Answer 1

It means that gdb is set to automatically infer the correct (programming) language from the source code associated with whatever frame you happen to be looking at.

From the GDB Manual:

15.1.3 Having gdb Infer the Source Language

To have gdb set the working language automatically, use set language
local' orset language auto’. gdb then infers the working language.
That is, when your program stops in a frame (usually by encountering a
breakpoint), gdb sets the working language to the language recorded
for the function in that frame. If the language for a frame is unknown
(that is, if the function or block corresponding to the frame was
defined in a source file that does not have a recognized extension),
the current working language is not changed, and gdb issues a warning.

This may not seem necessary for most programs, which are written
entirely in one source language. However, program modules and
libraries written in one source language can be used by a main program
written in a different source language. Using `set language auto’ in
this case frees you from having to set the working language manually.