Fastlane Best Practices for iOS and Troubleshooting Tips

Fastlane is a powerful tool for automating the tedious tasks in iOS development. Here are some best practices to get the most out of Fastlane:

Fastlane Best Practices for iOS

Keep Fastfile Clean

Your Fastfile should be as clean as possible. Use lanes to organize your tasks and keep them small and focused.

lane :test do
  scan
end

lane :beta do
  increment_build_number
  build_app
  upload_to_testflight
end

Use .env Files

Fastlane supports .env files which can be used to store sensitive data like API keys, passwords etc. This helps in keeping your Fastfile clean and your secrets safe.

# .env.default
APPLE_ID = "your-apple-id"
TEAM_ID = "your-team-id"

Use Fastlane Actions

Fastlane comes with a lot of built-in actions. Use them to automate tasks like running tests, building your app, incrementing build numbers, uploading to TestFlight etc.

lane :beta do
  increment_build_number
  build_app
  upload_to_testflight
end

Use Private Lanes

Private lanes can be used to break down complex tasks into smaller ones. They are not visible outside the Fastfile and can be called from other lanes.

lane :beta do
  increment_build_number
  build_app
  private_lane
end

private_lane :private_lane do
  # do something
end

Error Handling

Fastlane will stop executing as soon as it encounters an error. You can use begin/rescue blocks to handle errors and perform cleanup tasks.

lane :beta do
  begin
    increment_build_number
    build_app
    upload_to_testflight
  rescue => ex
    # handle error
    UI.message("Caught an error: #{ex}")
  end
end

Use Plugins

Fastlane has a rich ecosystem of plugins. Use them to extend Fastlane’s functionality. Fastlane plugins extend the functionality of Fastlane, allowing you to do more with your automation scripts. Here’s how you can use them:

Find a Plugin: You can find a list of available plugins on the Fastlane plugins directory . Choose a plugin that suits your needs.
Add the Plugin: Once you’ve found a plugin, you can add it to your project by running the following command in your terminal:

fastlane add_plugin [plugin_name]

Replace [plugin_name] with the name of the plugin you want to add. e.g.

# use `versioning` plugin to allows to set/get app version and build number directly to/from Info.plist
fastlane add_plugin versioning

Use the Plugin: After adding the plugin, you can use it in your Fastfile. The usage will depend on what the plugin does. You can usually find usage instructions on the plugin’s documentation page.

For example, if you’re using the fastlane-plugin-slack plugin, you can use it in your Fastfile like this:

lane :beta do
  increment_build_number
  build_app
  upload_to_testflight
  slack(message: "App has been uploaded to TestFlight!")
end

Update the Plugin: To update the plugin to the latest version, you can run the following command:

fastlane update_plugins

Use fastlane command line instead of `Fastfile`

Common Task: Increase Version

Common Task: Upload to TestFlight

Common Task: Update App Metadata

Continuous Integration

Fastlane works great with CI/CD tools. You can set up lanes to run on specific events like a push to a certain branch, a pull request etc.

Troubleshooting

Fastlane is a robust tool, but like any software, it can sometimes run into issues.

You don’t have write permissions for the /Library/Ruby/Gems/

Symptom

$ bundle install --path vendor/bundle
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems.rb:283:in `find_spec_for_exe': Could not find 'bundler' (2.1.4) required by your Gemfile.lock. (Gem::GemNotFoundException)
To update to the latest version installed on your system, run `bundle update --bundler`.
To install the missing version, run `gem install bundler:2.1.4`
	from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems.rb:302:in `activate_bin_path'
	from /usr/bin/bundle:23:in `<main>'
make: *** [setup] Error 1

$ gem install bundler:2.1.4
Fetching bundler-2.1.4.gem
ERROR:  While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions for the /Library/Ruby/Gems/2.6.0 directory.

This error usually occurs when trying to install a gem without the proper permissions.

Solution: Use a version manager like rbenv or rvm to manage your Ruby environment. This allows you to install gems without needing root permissions.

Solution

Use a version manager like rbenv or rvm to manage your Ruby environment. This allows you to install gems without needing root permissions.

# Install rbenv
brew install rbenv

# Initialize rbenv
rbenv init

# Install Ruby
rbenv install 2.7

# Set Ruby version for the project
rbenv local 2.7

Remember, the goal of using Fastlane is to automate as much as possible and make your development process smoother and more efficient. Happy coding!

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Fastlane Best Practices for iOS and Troubleshooting Tips