Anagram

A command line tool built to test the performance of various anagram checking methods.

Included are multiple versions of the function:

func isAnagram(string1: String, string2: String) -> Bool {

}

Unit tests are also included to ensure that each version of isAnagram works as expected.

Rules

• ignore capitalization (given the strings "cow" and "Cow", the function should return true)
• ignore spaces (given the strings "Mia" and "I am", the function should return true)

Why?

During a job interview I was given a "whiteboard" code challenge with this problem. After the interview I was curious and wanted to find a way to solve it that performed well with large strings.

Some ideas came from various members of the iOS Developers Slack group.

Key take-aways

• Version 2 (isAnagramV2) is the fastest, though it might not be the answer an interviewer is looking for during a whiteboard job interview.
• Originally I had written this in a Playground, but performance testing in a Playground is generally not a good idea. Testing the compiled code via this command line tool provides more accurate results.
• Performance differences between the debug build and release build can be dramatic. On my computer, isAnagramV2 takes 10s when running the debug build, and less than 1s for the release build. So, it's best to test performance on the release build.