ERROR: Identical Key For Two Renditions (Xcode 10.1, Mojave 10.14.1)

Resolving the "ERROR: Identical key for two renditions" Issue in Xcode 10.1 on macOS Mojave

Introduction

When attempting to convert a macOS app from High Sierra (Xcode 9.x) to Mojave (Xcode 10.1), developers may encounter a frustrating error in their Asset.xcassets file. The error message "ERROR: Identical key for two renditions" can be puzzling, especially when you're not sure what's causing it. In this article, we'll delve into the possible causes of this error and provide step-by-step solutions to resolve it.

Understanding the Error

The "ERROR: Identical key for two renditions" error occurs when Xcode encounters two or more renditions (e.g., @2x, @3x) with the same key in your Asset.xcassets file. This can happen when you're migrating your project from an older version of Xcode or when you're adding new assets to your project.

Possible Causes of the Error

Before we dive into the solutions, let's explore the possible causes of this error:

• Duplicate renditions: When you have multiple renditions with the same key, Xcode gets confused and throws an error.
• Missing or incorrect asset catalog settings: If your asset catalog settings are not properly configured, Xcode may not be able to resolve the renditions correctly.
• Legacy project settings: When migrating a project from an older version of Xcode, some legacy settings may cause issues with the asset catalog.

Step-by-Step Solutions

To resolve the "ERROR: Identical key for two renditions" issue, follow these steps:

1. Check for Duplicate Renditions

Open your Asset.xcassets file and inspect the contents. Look for any duplicate renditions with the same key. If you find any, delete the duplicate rendition.

**Asset.xcassets**
*   Rendition 1 (e.g., @2x)
*   Rendition 2 (e.g., @3x)
*   Duplicate Rendition (e.g., @2x)

Delete the duplicate rendition and save the file.

2. Review Asset Catalog Settings

Open your project's target settings and navigate to the General tab. Scroll down to the Asset Catalog section and ensure that the Asset Catalog is set to Current.

**Target Settings**
*   General
*   Asset Catalog
*   Current

If the Asset Catalog is set to Legacy, change it to Current and save the file.

3. Update Legacy Project Settings

If you're migrating a project from an older version of Xcode, some legacy settings may cause issues with the asset catalog. To resolve this, follow these steps:

• Open your project's .xcconfig file (e.g., MyProject.xcconfig).
• Look for the ASSET_CATALOG_MODE setting and update it to Current.
• Save the file.

**.xcconfig**
ASSET_CATALOG_MODE = Current

4. Clean and Rebuild the Project

After making the above changes, clean and rebuild your project to ensure that the changes take effect.

**Clean and Rebuild**
*   Product > Clean
*   Product > Build

Conclusion

The "ERROR: Identical key for two renditions" issue in Xcode 10.1 on macOS Mojave can be frustrating, but it's often caused by simple issues like duplicate renditions or incorrect asset catalog settings. By following the step-by-step solutions outlined in this article, you should be able to resolve the issue and get your project up and running smoothly.

Additional Tips

• When working with asset catalogs, it's essential to keep your renditions organized and up-to-date.
• Regularly clean and rebuild your project to ensure that any changes take effect.
• If you're still experiencing issues, try resetting your Xcode preferences or seeking help from the Xcode community.

Related Resources

• Apple Developer Documentation: Asset Catalogs
• Xcode 10.1 Release Notes
• Stack Overflow: ERROR: Identical key for two renditions
  Frequently Asked Questions: Resolving the "ERROR: Identical key for two renditions" Issue in Xcode 10.1 on macOS Mojave

Q: What causes the "ERROR: Identical key for two renditions" issue in Xcode 10.1 on macOS Mojave?

A: The "ERROR: Identical key for two renditions" issue in Xcode 10.1 on macOS Mojave is caused by duplicate renditions with the same key in your Asset.xcassets file. This can happen when you're migrating your project from an older version of Xcode or when you're adding new assets to your project.

Q: How do I identify duplicate renditions in my Asset.xcassets file?

A: To identify duplicate renditions in your Asset.xcassets file, open the file and inspect the contents. Look for any duplicate renditions with the same key. If you find any, delete the duplicate rendition.

Q: What are the possible causes of the "ERROR: Identical key for two renditions" issue?

A: The possible causes of the "ERROR: Identical key for two renditions" issue include:

• Duplicate renditions
• Missing or incorrect asset catalog settings
• Legacy project settings

Q: How do I resolve the "ERROR: Identical key for two renditions" issue?

A: To resolve the "ERROR: Identical key for two renditions" issue, follow these steps:

1. Check for duplicate renditions in your Asset.xcassets file and delete any duplicates.
2. Review your asset catalog settings and ensure that the Asset Catalog is set to Current.
3. Update any legacy project settings to resolve the issue.
4. Clean and rebuild your project to ensure that the changes take effect.

Q: What are the benefits of using asset catalogs in Xcode?

A: Asset catalogs in Xcode provide several benefits, including:

• Simplified asset management
• Improved performance
• Enhanced user experience

Q: How do I optimize my asset catalog for better performance?

A: To optimize your asset catalog for better performance, follow these best practices:

• Use the Current asset catalog mode
• Ensure that your asset catalog is properly configured
• Regularly clean and rebuild your project

Q: What are some common issues that can occur with asset catalogs in Xcode?

A: Some common issues that can occur with asset catalogs in Xcode include:

• Duplicate renditions
• Missing or incorrect asset catalog settings
• Legacy project settings

Q: How do I troubleshoot issues with my asset catalog in Xcode?

A: To troubleshoot issues with your asset catalog in Xcode, follow these steps:

1. Check your asset catalog settings and ensure that they are properly configured.
2. Review your project settings and ensure that they are up-to-date.
3. Clean and rebuild your project to ensure that the changes take effect.
4. Seek help from the Xcode community or Apple support if necessary.

Q: What are some best practices for working with asset catalogs in Xcode?

A: Some best practices for working with asset catalogs in Xcode include:

• Regularly clean and rebuild your project
• Use the Current asset catalog mode
• Ensure that your asset catalog is properly configured
• Use asset catalogs for all assets, including images, icons, and more

Q: How do I reset my Xcode preferences to resolve issues with my asset catalog?

A: To reset your Xcode preferences, follow these steps:

1. Open Xcode and go to Xcode > Preferences.
2. Click on Reset and then click on Reset All.
3. Restart Xcode and try again.

Q: What are some additional resources for learning more about asset catalogs in Xcode?

A: Some additional resources for learning more about asset catalogs in Xcode include:

• Apple Developer Documentation: Asset Catalogs
• Xcode 10.1 Release Notes
• Stack Overflow: ERROR: Identical key for two renditions

Conclusion

The "ERROR: Identical key for two renditions" issue in Xcode 10.1 on macOS Mojave can be frustrating, but it's often caused by simple issues like duplicate renditions or incorrect asset catalog settings. By following the step-by-step solutions outlined in this article, you should be able to resolve the issue and get your project up and running smoothly. Remember to regularly clean and rebuild your project, use the Current asset catalog mode, and ensure that your asset catalog is properly configured for optimal performance.