Swift: #warning equivalent

Question

Does Swift have a #warning equivalent? It\'s simply used to show a warning in Xcode\'s own GUI

I\'m also interested in whether there\'s a #error equivalent.

Answer 1

After much searching and longing, I'm convinced no such entity exists. I'm still hopeful with the latest Xcode release notes mentioning the continued lack of a #pragma mark mechanism, #warning and #error may also be coming as well.

As an aside, I highly recommend filing a Radar with Apple at bugreport.apple.com to add this functionality (you can dupe 17702491).

Answer 2

As an alternative, if you want something to show up in the warnings panel, you could write something like:

if (false){
   var x = 2;
}

You can't really get any text to show up, but at least it's a more visible marker, especially if you tend to treat (most) warnings like errors.

Answer 3

We wrote a configurable tool that lets you put warnings and errors in Xcode Issue Navigator based on comment tag and build configuration: https://github.com/doubleencore/XcodeIssueGenerator

Install it:

brew tap doubleencore/tap
brew install xcodeissuegenerator

Then put a line in a Run Script Build Phase:

# Mark WARNINGs, SERIOUSs, and TODOs as warnings in DEBUG builds excluding the Vendor and Third Party directories.
XcodeIssueGenerator -b DEBUG -w "WARNING, SERIOUS, TODO" -x "Vendor/, Third Party/"

Here's an article describing how we use it.

Answer 4

If you’re loath to adjust your build setup, another simple home remedy is to stick an editor placeholder in front of the comment:

<#todo#>// stop and fixme!

You get an “Editor placeholder in source file” error when you build, but unlike Jordan’s solution, there’s no live error to annoy you while typing:

Answer 5

Post WWDC 2018 Update

Starting with Xcode 10 and Swift 4.2 you will now be able to use #warning again like so:

#warning("TODO: Clean up this code after testing")

This will show up as a warning in Xcode just as expected!

This works even in combination with #if checks, for example the following will only show a warning if your target platform is iOS:

#if os(iOS)
    #warning("this code is untested in iOS")
#endif

There's also #error if you want your build to fail.

---

Pre WWDC 2018 Answer

In Swift using XCode 6 you can use different kinds of landmarks for different purposes. Here's what Apple says about it:

Xcode now supports //MARK:, //TODO: and //FIXME: landmarks to annotate your code and lists them in the jump bar.

So for setting a warning with a description you would use something like this:

//TODO: Clean up this code after testing

If you just want to set a short mark (assuming you will remember what to do), use this:

//FIXME

EDIT: These landmarks however only appear in the jump bar of XCode which might not be what you wish for and what one would expect – especially from the //TODO: and //FIXME marks. I've filed a radar on that: #17776817. Hopefully Apple will add this in the coming builds in XCode 6.

SOLUTION (EDIT 2): If you install the Swift Linter via Homebrew (run brew install swiftlint after a brew update) and add the suggested build script to your project, then you will see all your TODO and FIXME landmarks appear as warnings within Xcode. SwiftLint will even add some more warnings/errors that you can configure to fit your needs – I can only recommend using SwiftLint and it solves this problem in a great way!

Answer 6

I may be late to the party with Xcode 10 supporting errors and warnings, but simply putting a String:

"Need to finish implementing this"

will produce a warning: String literal is unused with autocompletion still working and the project still compiling.