Turn off Xcode's unused variable warnings while typing

Question

I'm sick to death of Xcode's prolific use of live "unused variable" warnings while I am typing. I keep thinking I have an error in my syntax, stop what I'm doing, check the warning, only to see it's an unused variable warning.

Of course it's unused, I just typed it!

I don't mind the compile-time unused variable warnings, those are very useful, but I hate the live warnings as I'm typing code.

Is there any way I can turn off this warning completely everywhere, either app-wide or for an entire project?

Answer 1

It seems as of currently, we cannot suppress specific warnings in the way #pragma clang diagnostic ... could be used for obj-C. See e.g. the following thread

• How to suppress a specific warning in Swift

---

There is possible to disable all interactive warnings globally, by disabling Show live issues, from Xcode -> Preferences: Tab General. This, however, in excess of disabling all live warnings, also disable live errors, so something I presume you wouldn't want to resort to.

---

[Build warnings] You can turn off custom build warnings project-wide as follows:

• Select your project in the navigator, and choose tab Build Settings. Find Apple LLVM 7.0 - Warnings - All Languages, and disable the warnings for Unused Values and Unused Variables.

Answer 2

On my version (Xcode 10.2.1), it seems as if disabling live warnings only disables warnings, not all errors as others have said. So, I would think this exact answer addresses the original post quite well:

Xcode > Preferences > General > Issues: [x] Show live issues

Uncheck "Show live issues". No more constant warnings as you type new code.

Answer 3

@warn_unused_result is a default behavior as of Xcode 10 (swift 4.2). 'Unused Values' and 'Unused Variables' warnings are also on by default. It is not a very good idea to turn them off and this answer shows why. For your own or overridden funcs you can use @discardableResult directive in declaration to suppress these warnings like this:

Note that doSubmission() does not generate any warnings.

In fact this is used in some system API, for example: if you write

navigationController?.popToRootViewController(animated: true)

instead of

_ = navigationController?.popToRootViewController(animated: true)

you'll get no warning for ignoring the result returned.

Using _ = funcWithResultWeDoNotCareFor() is the best practice IMHO.

BTW, that all works for project. In Playground you will not get 'Unused Values' and 'Unused Variables' warnings no matter what.