How to easily clean up the unused images and resources in your projects

Photo by Christina Morillo on Pexels

Unused images can exist as a result of different iterations in a project. Once a feature is no longer needed and removed, it isn’t always cleaned up completely. Therefore, it’s useful to know how to clean up your Xcode assets.

Just like in my blog post on cleaning up unused localized strings, I’ll go over a couple of tools you can use to clean up your project:

Unfortunately, a lot of tools like Slender that used to do the job are no longer maintained. Therefore, let’s see what is working nowadays!

For this, I’m going to use my day-to-day job project Collect by WeTransfer. The assets in this project haven’t been cleaned in two years.


Cleaning Up Unused Images Using FengNiao

FengNiao is a command-line tool mostly written in Swift. It’s open-source and available on Github. It can be installed by cloning the repository and running the install script:

> git clone https://github.com/onevcat/FengNiao.git
> cd FengNiao
> ./install.sh

Using it is as simple as changing the directory to your project folder in the terminal and executing FengNiao:

> fengniao

It will show you the results first, and then you’ll have the option to delete, ignore, or list the unused resources.

Searching unused file. This may take a while...
218 unused files are found. Total Size: 19.09 MB
What do you want to do with them? (l)ist|(d)elete|(i)gnore

Listing the files showed that the dependencies were also checked. Obviously, we don’t want to focus on those as they’re not managed by us.

1.57 KB /Users/antoinevanderlee/Documents/GIT-Projects/WeTransfer/Coyote/Submodules/Rabbit/Submodules/Alamofire/docs/docsets/Alamofire.docset/Contents/Resources/Documents/img/gh.png

Apart from listing dependency assets, the tool is also listing images for documentation folders. Therefore, we need to run the tool again with a few extra options.

We can list all available options by using the — help parameter.

$ fengniao --help
Usage: fengniao [options]
-p, --project:
Root path of your Xcode project. Default is current folder.
--force:
Delete the found unused files without asking.
-e, --exclude:
Exclude paths from search.
-r, --resource-extensions:
Resource file extensions need to be searched. Default is 'imageset jpg png gif'
-f, --file-extensions:
In which types of files we should search for resource usage. Default is 'm mm swift xib storyboard plist'
--skip-proj-reference:
Skip the Project file (.pbxproj) reference cleaning. By skipping it, the project file will be left untouched. You may want to skip ths step if you are trying to build multiple projects with dependency and keep .pbxproj unchanged while compiling.
--version:
Print version.
-h, --help:
Print this help message.

The exclude option is the one we need. After looking into all the paths listed for Collect, it turned out that we could ignore quite a few paths. This results in the following command:

fengniao --exclude Carthage Pods Submodules Vendor guides fastlane

This tells the tool to ignore the folders that contain the dependencies, as well as our documentation and Fastlane folder. The final result contains 44 unused resources to clean up:

Unused images clean up using Fengniao
Unused images clean up using Fengniao
Unused images clean up using FengNiao

To verify that these are unused assets, I randomly picked a few and did a search in Xcode. It turned out that those assets are indeed unused and could be cleaned up.

Running the tool again proved that it’s working as expected!

$ fengniao --exclude Carthage Pods Submodules Vendor guides fastlane
Searching unused file. This may take a while...
😎 Hu, you have no unused resources in path: /Users/antoinevanderlee/Documents/GIT-Projects/WeTransfer/Coyote.

Unused Images Clean Up Using LSUnusedResources

LSUnusedResources is a Mac app that does exactly the same thing as FengNiao: cleaning up unused images and resources. It’s open-source as well, but it’s no longer maintained. At the moment of writing, the last commit already dates back to a year ago. However, it still runs and is therefore worth a try!

The executable can be downloaded from the Github page. It may tell you that it’s unsafe to open. If so, you can use Control + Open to open it. After running it with the default settings, it shows almost the same results as FengNiao:

Unused images result with LSUnusedResources
Unused images result with LSUnusedResources
Unused images result with LSUnusedResources

Just like we did with FengNiao, we should now run it again with the excluded folders. We have to fill in the Resource Suffix by separating the folders with a pipe symbol:

Carthage|Pods|Submodules|Vendor|guides|fastlane

The results:

Total: 106, unused: 21, time: 1.53s, size: 328.92

Those are all unused assets, and they can be easily removed using the delete button in the application.


Comparing the Results: FengNiao or LSUnusedResources?

Comparing the two outcomes shows some big differences:

FengNiao:          44 unused files / Total Size: 440.06 KB
LSUnusedResources: 21 unused files / Total Size: 328.92 KB

At first, this seems to be mainly related to the two extension targets which we have in Coyote. FengNiao is correctly checking those, but LSUnusedResources seems to ignore them.

To be entirely sure, I created a branch for each tool and compared the changes. This confirmed that FengNiao did a better job and found more unused resources.


Is It Always Safe to Clean Up Those Unused Images?

Definitely not! It’s a good idea to go over the assets before you delete them. There’s a common example of assets that are used but still listed as unused. This is when you build up a reference to a resource based on certain conditions.

For example, in Coyote we’re using the following code:

UIImage(named: "\(iconName)\(iconSize.sizeString)")

It turned out that all those images were listed in both results, and it’s therefore required to go over the results manually before deleting the images.


Bonus: Clean Up Your Xcode Developer Files

As you’re already into cleaning up, how about cleaning up your Xcode developer files as well?

There’s a great tool called DevCleaner that will easily delete up to 20GB of unused data for you. This is how it looked for me after running it for the first time:

Cleaning up your Xcode developer files using DevCleaner
Cleaning up your Xcode developer files using DevCleaner
Cleaning up your Xcode developer files using DevCleaner

Do know that this app will delete all your old iOS versions by default. For example, in my case, it selected all iOS 11 and 12 device support files, leaving me with device support for only iOS 13. This is obviously not what you want. Therefore, go through the selection and adjust it to your needs.


Conclusion

Cleaning up your project to delete unused images is definitely worth a try. It will keep your project clean and free from assets you’re no longer using. Keep a sharp eye, and go over the results manually before deleting them.

Better Programming

Advice for programmers.

Antoine van der lee 🇳🇱

Written by

iOS Developer @WeTransfer — Follow me on twitter.com/twannl for more tips & tricks — Blogging weekly at https://avanderlee.com

Better Programming

Advice for programmers.

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