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Hybrid Swift and Objective-C Codebase Management

1 post · Jun 2017

What this trail covers

Shopify has developed and enhanced strategies for maintaining hybrid Swift and Objective-C codebases, enabling the integration of new Swift code with existing Objective-C components. This involves leveraging Swift's type safety and modern features while ensuring seamless interoperability with Objective-C's runtime. Key techniques include using the `@objc` attribute for granular bridging control, wrapping Swift-only types in NSObject subclasses for Objective-C visibility, and utilizing Swift extensions to add Objective-C-visible methods as categories. This approach allows for the development of type-safe models in Swift and dynamic UI inflation in Objective-C, facilitating the adoption of Swift without a complete codebase rewrite.

All Shopify trails
  1. Maintaining a Swift and Objective-C Hybrid Codebase - ShopifyThis post details techniques for maintaining hybrid Swift and Objective-C codebases. It explains how Swift classes inheriting from Objective-C classes are automatically bridged, and how protocols annotated with `@objc` are visible in the Objective-C runtime. The `@objc` attribute is highlighted for its ability to specify Objective-C class and method names. The post also covers strategies for making Swift-only features like enums and structs accessible from Objective-C by wrapping them in NSObject subclasses with proxy methods. Furthermore, it demonstrates how Swift extensions can add Objective-C-visible methods to NSObject subclasses, effectively acting as categories and allowing for mixed-language code interaction. A specific workaround for incorrect nullability annotations in bridged Objective-C APIs is also presented.