Code Smells in Objective-C

Code smells. I’ve mentioned “code smells” at work, only to discover that my coworkers didn’t know what I meant. It’s basically a diaper-changing metaphor: “If it stinks, change it.”

Code Smells

diaper” by beth darbyshire, used under CC BY-NC-ND 2.0 / added text

“If it stinks, change it.”

A code smell isn’t “awful code that makes you hold your nose.” Rather, it’s a simple indication that something may need to be changed. Quite often, you won’t notice a code smell until someone else describes it. This is what Kent Beck and Martin Fowler did in the Refactoring book: created a list of smells, and what to do about them.

Code Smells Specific to Objective-C

The book’s catalog of code smells relate to good practices of object-oriented programming. I’m going to start a series that is specific to Objective-C code smells. Here’s a tentative list to give you a preview:

  1. 9 Code Smells of Xcode Preprocessor Macros
  2. #imports Gone Wild! How to Tame File Dependencies
  3. 4 Ways Precompiled Headers Cripple Your Code
  4. Is Dot Notation in Objective-C 100% Pure Evil?
    …or maybe not! I switched, see In Which I Embrace Dot Notation…
  5. Objective-C init: Why It’s Helpful to Avoid Messages to self

I think this’ll be interesting, and sometimes even controversial. (Dot notation, anyone?) So be sure to come back — subscribe to keep up with the latest postings!

Other resources:

Question: What common Objective-C practices have you encountered that you might consider code smells? Leave a comment below.

About the Author Jon Reid

When I was a kid, programming was fun. But working in Silicon Valley, I saw poor code lead to fear, with real human costs. Searching for ways to make life better, I learned about Design Patterns, Refactoring, and Test Driven Development (TDD). Programming became fun again! I've now been doing TDD in Apple environments for 17 years. I'm committed to software crafting as a discipline, with the hope of raising us all to greater effectiveness and joy.

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  • Hi Jon,
    I think you’ve picked a great topic here. I know that there will be things that I will be able to learn from. I look forward to your next post.
    Take care,

  • Jon,
    I’m looking forward to your series. You have me curious about #4 :-)

  • Eimantas says:

    Just after reading that “Preprocessor use” may cause code smell I became instantly intrigued. Would you mind giving me a hint of what that might be?

  • Mayur says:

    Hi Jon,
    Great topic!!.
    Looking forward to your next post. – Mayur

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