iOS Deployment Target in Flutter

Problem

When building a Flutter iOS application, you may encounter warnings indicating that the iOS deployment target IPHONEOS_DEPLOYMENT_TARGET is set to 8.0, but the supported deployment target version range is 9.0+:

warning: The iOS deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.0.99. (in target 'gRPC-C++-gRPCCertificates-Cpp' from project 'Pods')

These warnings typically appear after updating Xcode, Flutter, or when adding new dependencies that require a higher minimum iOS version.

Understanding the Issue

The error occurs because:

• Modern Xcode versions (Xcode 12+) only support iOS deployment targets from 9.0 to the current version
• Some Flutter dependencies still reference the legacy deployment target of 8.0
• The Podfile configuration may not be properly setting the deployment target for all pods

WARNING

While these are warnings rather than errors, they can sometimes indicate underlying compatibility issues that may cause build failures.

Solutions

Method 1: Update Podfile Configuration (Recommended)

The most effective solution is to update your ios/Podfile:

# Set platform at the top of the file
platform :ios, '11.0' # Set to your minimum supported version

# Add post_install script at the end of the file
post_install do |installer|
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = '11.0' # Match the version above
    end
  end
end

Method 2: Update Xcode Project Settings

1. Open your Flutter project in Xcode (ios/Runner.xcworkspace)
2. Select the "Runner" project in the project navigator
3. Under "Info" tab, set "iOS Deployment Target" to your desired minimum version (9.0 or higher)
4. Update ios/Flutter/AppFrameworkInfo.plist:
   • Change MinimumOSVersion to your desired minimum version

Method 3: Clean and Rebuild

Sometimes, cleaning the build artifacts resolves the issue:

flutter clean
rm ios/Podfile.lock
rm -rf ios/Pods
rm -rf ios/Runner.xcworkspace
flutter pub get
cd ios && pod install --repo-update

Method 4: Update Flutter and Dependencies

Ensure you're using a recent Flutter version and that all dependencies are up to date:

flutter upgrade
flutter pub outdated
flutter pub upgrade

Platform-Specific Deployment Targets

For different Apple platforms, use the appropriate build settings in your Podfile:

iOS

config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = '11.0'

macOS

config.build_settings['MACOSX_DEPLOYMENT_TARGET'] = '11.0'

tvOS

config.build_settings['TVOS_DEPLOYMENT_TARGET'] = '14.0'

watchOS

config.build_settings['WATCHOS_DEPLOYMENT_TARGET'] = '7.0'

Troubleshooting

If Build Still Fails

If you continue to experience issues after applying these fixes:

1. Check for real errors: The warnings might be masking actual build errors. Search your build output for "error" to identify the real problem
2. Remove conflicting packages: Some packages may not be compatible with newer iOS versions
3. Recreate iOS folder: As a last resort, delete the ios folder and regenerate it:

rm -rf ios
flutter create --platforms=ios .

DANGER

Recreating the iOS folder will remove all custom iOS-specific configurations, so back up any important changes first.

Firebase and Other Dependencies

If using Firebase or other services that might have legacy dependencies:

1. Ensure you're using the latest versions of Firebase Flutter plugins
2. Check for any required post-installation steps in the plugin documentation
3. Verify that all Run Script phases in Xcode are up to date with the latest requirements

Best Practices

1. Set a reasonable minimum version: iOS 11.0+ is generally recommended as it covers most devices still in use
2. Keep dependencies updated: Regularly update your Flutter SDK and packages
3. Test on multiple devices: Ensure your app works correctly on the minimum version you specify
4. Document your minimum version: Update your app's documentation and store listings with the supported iOS versions

Conclusion

The iOS deployment target warning is a common issue when working with Flutter iOS builds. By properly configuring your Podfile and Xcode project settings, you can resolve these warnings and ensure your app builds successfully with the appropriate minimum iOS version.