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# Objective-C and C Code Customization

Apply macros to your Objective-C APIs to customize how they’re imported into Swift.

## Topics

### Customizing Objective-C APIs

  <doc://com.apple.Swift/documentation/Swift/designating-nullability-in-objective-c-apis>

  <doc://com.apple.Swift/documentation/Swift/renaming-objective-c-apis-for-swift>

  <doc://com.apple.Swift/documentation/Swift/improving-objective-c-api-declarations-for-swift>

  <doc://com.apple.Swift/documentation/Swift/grouping-related-objective-c-constants>

  <doc://com.apple.Swift/documentation/Swift/marking-api-availability-in-objective-c>

  <doc://com.apple.Swift/documentation/Swift/making-objective-c-apis-unavailable-in-swift>

### Customizing C APIs

  <doc://com.apple.Swift/documentation/Swift/customizing-your-c-code-for-swift>


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