The Mysterious Case of Xcode Scheme’s Build Pre-Action Output: Unveiling the Truth

As an iOS developer, have you ever wondered what’s happening behind the scenes during the build process of your Xcode scheme? Specifically, have you ever asked yourself, “Is there any way to view output from an Xcode scheme’s build pre-action / verify it completed successfully?” Well, wonder no more! In this article, we’ll embark on a thrilling adventure to demystify the build pre-action output and provide you with the answers you’ve been searching for.

The Enigmatic Build Pre-Action

A build pre-action is a script that runs before the actual build process begins. It’s a powerful feature in Xcode that allows you to perform various tasks, such as cleaning up the project directory, generating files, or even making a cup of coffee (just kidding, but wouldn’t that be awesome?). The problem is, once you’ve set up your build pre-action, it can be challenging to verify its success or even view its output.

The Quest for Visibility

So, how do you peek into the mysterious world of build pre-actions? Fear not, dear developer, for we have a few tricks up our sleeves. Let’s explore some methods to view the output and verify the success of your build pre-action.

Method 1: Xcode Console

The most straightforward approach is to use the Xcode console. Yes, you read that right – the console! It’s often overlooked, but it’s an excellent tool for debugging and monitoring your build process. To access the console, follow these steps:

1. Open your Xcode project.
2. Click on the “Product” menu and select “Clean” (or press Shift + Command + K).
3. Click on the “Product” menu and select “Build” (or press Command + B).
4. In the Xcode menu bar, click on “View” and select “Debug Area” (or press Command + Shift + Y).
5. In the Debug Area, click on the “Console” tab.

In the console, you’ll see the output of your build pre-action. Look for the section labeled “Run script” or “Build pre-action,” and you’ll find the output of your script.

${WRAPPER_NAME}: warning: Run script build phase '[CP] Embed Pods Frameworks' will run because output '[CP] Embed Pods Frameworks' was modified.
[...]
[CP] Embed Pods Frameworks
[...]
** BUILD SUCCEEDED **

Method 2: Redirecting Output to a File

Sometimes, you might want to redirect the output of your build pre-action to a file for further analysis or logging purposes. You can achieve this by modifying your script to write the output to a file. Here’s an example:

#!/bin/bash

# Your build pre-action script goes here...

# Redirect output to a file
echo "Build pre-action output:" >> "${PROJECT_DIR}/build_pre_action_output.log"

# Continue with the rest of the script...

In this example, the output of your build pre-action will be appended to a file named “build_pre_action_output.log” in your project directory. You can then easily open and view the file to see the output.

Method 3: Using the Xcode Server

If you’re using Xcode Server, you can take advantage of its built-in logging features. Xcode Server provides a more extensive logging system, which includes the output of your build pre-action. To access the logs, follow these steps:

1. Open the Xcode Server web interface.
2. Click on the “Logs” tab.
3. Select the build that corresponds to your project.
4. In the log viewer, click on the “raw” tab.
5. Search for the “Build pre-action” section.

In the log viewer, you’ll find the output of your build pre-action. You can also download the log files for further analysis.

Verifying Success

Now that you’ve managed to view the output of your build pre-action, it’s essential to verify its success. You can do this by checking the exit status of your script. In Xcode, you can use the ${EXIT_STATUS} variable to check the exit status of your script.

#!/bin/bash

# Your build pre-action script goes here...

# Check the exit status
if [ $? -eq 0 ]; then
  echo "Build pre-action completed successfully!"
else
  echo "Build pre-action failed with exit code $?!"
  exit 1
fi

In this example, if the script executes successfully, the exit status will be 0, and the script will print a success message. If the script fails, the exit status will be non-zero, and the script will print an error message and exit with a non-zero status.

Conclusion

In conclusion, viewing the output of an Xcode scheme’s build pre-action and verifying its success might seem like a daunting task, but fear not, dear developer! With the methods outlined in this article, you now have the tools to demystify the build pre-action process. Whether you use the Xcode console, redirect output to a file, or leverage the Xcode Server logs, you’ll be well-equipped to monitor and debug your build pre-action.

So, the next time you’re wondering what’s happening behind the scenes during the build process, remember: knowledge is power! Take control of your build pre-action and unleash the full potential of your Xcode scheme.

Method	Description
Xcode Console
Redirecting Output to a File	Redirect the output of your build pre-action to a file for further analysis or logging purposes.
Xcode Server	Use the Xcode Server logs to view the output of your build pre-action.

Additional Resources

• Xcode 12 Release Notes: Build System Improvements
• Xcode Build System Guide
• NSHipster: Xcode Build Actions

We hope you’ve enjoyed this comprehensive guide to viewing the output of an Xcode scheme’s build pre-action. Happy coding, and may the build be with you!

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