Context

As Beeda expanded with new features, compile times began to pose a serious challenge. A simple change or full compilation took around 11 minutes, slowing down our workflow significantly.

To enhance productivity and streamline development, we aimed to drastically reduce this compile time. In this article, I’ll walk you through how we successfully brought it down to just 2 minutes.

Optimization Levels in Xcode

Xcode provides three optimization levels to choose from:

  • None
  • Fast
  • Fast with Whole Module Optimization

Here’s how we leveraged these settings to achieve this improvement.

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Enabling Whole Module Optimization greatly accelerates the compilation process. However, selecting the Fast or Fast with Whole Module Optimization settings disables debugging functionality. After choosing one of these options and compiling the app, attempting to debug results in the following message in the console:

App was compiled with optimization - stepping may behave oddly; variables may not be available.

Solution: Add a User-Defined Setting

To enable full module optimization, you’ll need to manually add a User-Defined Setting in your Xcode project configuration. Here’s how you can do it:

Steps

  1. Navigate to Project Settings:

    • In the Project Navigator, select your project.
    • Go to the Build Settings tab.

  2. Add a User-Defined Setting:

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    • Click the + button in the top-left corner of the Build Settings pane.
    • Select Add User-Defined Setting.
    • Name the setting SWIFT_WHOLE_OPTIMIZATION_LEVEL (or another relevant name).
    • Set its value to YES to enable full module optimization.

  3. Set None in Debug configuration

    • From target build settings set Optimization Level to None in Debug configuration

How Does This Impact Beeda?

For our iOS team, which frequently updates and iterates on our code, this enhancement plays a significant role in improving efficiency, reducing costs, and enhancing the customer experience. To put it into perspective, if we run 30 compilations each day, this optimization saves us roughly 26 hours of compilation time per day. This time savings is akin to having the output of three extra developers on the team.