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Omit Needless Words

To promote clear usage, the Swift API Design Guidelines advice that we omit needless words in function names. Words that merely repeat type information are specifically identified as needless.

This is a tool that helps you spot those words in your code base.


Prerequisite: have Swift 3 installed on your system.

  1. Clone or download content of this repository.
  2. run make.



The command needless can process text from STDIN or files specified in a list of paths. The simplest way to use it is one of the following:

needless path/to/file1.swift path/to/file2.swift
echo "func someName(foo bar: Baz..." | needless

needless will print out function names with needless words and suggest an alternative.

Run needless -h for more details, or read the next section.


Several output formats are included for different use scenarios. They make this command more useful when combined with other scripts/tools.

  • By default, needless prints output in a readable format:

    potential needless words in first parameter label in path/to/file.swift (line 87)
        private func buttonTitleColor(forType type: NewsfeedItemType) -> UIColor {
    possible alternative: func buttonTitleColor(for type: NewsfeedItemType …
  • Use the option -Xcode for clang/swiftc style warning:

    needless -Xcode path/to/file.swift
    path/to/file.swift:23:5: warning: potential needless words in function name 'func testWithData(_ data: Data …'; perhaps use 'func test(with data: Data …' instead?

    This means you can add needless as a build phase in Xcode to get inline highlighting.

    needless in Xcode

    1. add a "Run Script" build phase in your Xcode project and paste in the following:

      needless -dollar path/to/file.swift
      IFS=$'\n' find . -name "*.swift" -exec needless -Xcode {} \;

      (customize the command according to your needs. e.g. you may want to change the path . to Sources to avoid warnings for files in Packages or Pods folder).

    2. build your Xcode project.

  • -dollar prints results in $-separated strings:

    needless -dollar path/to/file.swift
    potential needless words in function name$path/to/file.swift$22$4$func testWithData(_ data: Data$func test(with data: Data

    That's [description]$[path]$[line number]$[column number]$[original name]$[suggested name]

    This format is convenient for parsing and further actions. It's trivial to read it and do automated replacement, for example.

  • -diff will make needless only process lines that begin with character +, ! or >. This is handy when you are dealing with patch formats. Make needless part of your git hooks!

    -diff can be combined with -dollar and -Xcode.

Not a robot

The API guideline starts with "every word in a name should convey salient information at the use site". needless isn't AI with advanced natural language processing capabilities (yet?). In fact, it assumes you use camelCase in function names and merely tries to find problematic function names in a very mechanical (dumb) way. Its suggestions are often awkward/too aggressive. Always prioritize good human judgement please :)


A utility to find needless words in Swift function names.







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