🔰Extensions

⭐️ 重點

Extensions in Swift can:

• Add computed instance/type properties.

• Define instance/type methods.

• Provide new initializers.

• Define subscripts.

• Define and use new nested types.

• Make an existing type conform to a protocol.

• (Protocol Extensions) provide default implementations or add additional functionality.

🔴 主題

• extension of nested types

• extension of typealias❓

📘 手冊

• Swift ⟩ Extensions

👥 相關

• can define nested types.