能否扩展CoreData属性？为实体属性添加固定枚举标识的问询

Absolutely, this idea is totally workable—you’re on the right track with a function to map entity attributes to a visibility enum. Since the visibility rule is entity-level (fixed per attribute, not per record), we don’t need to store this enum in CoreData at all; we can handle it entirely in code. Here are a couple of clean implementation patterns:

1. Entity Extension + Static Method (Most Straightforward) #

For each CoreData entity (like Product), create an extension that defines your visibility enum and a static function to return the visibility for a given attribute. This keeps the logic tightly coupled to the entity it belongs to.

First, define the visibility enum:

enum ProductAttributeVisibility: String {
    case `public`
    case `private`
}

Then add an extension to your Product entity:

extension Product {
    // Option 1: String-based attribute lookup (use #keyPath to avoid typos)
    static func visibility(for attribute: String) -> ProductAttributeVisibility? {
        switch attribute {
        case #keyPath(Product.name):
            return .public
        case #keyPath(Product.price):
            return .private
        default:
            return nil
        }
    }

    // Option 2: Type-safe KeyPath lookup (even better for avoiding mistakes)
    static func visibility<T>(for keyPath: KeyPath<Product, T>) -> ProductAttributeVisibility? {
        switch keyPath {
        case \Product.name:
            return .public
        case \Product.price:
            return .private
        default:
            return nil
        }
    }
}

To use it:

// String-based
if let nameVisibility = Product.visibility(for: #keyPath(Product.name)) {
    print("Name is \(nameVisibility.rawValue)")
}

// KeyPath-based (safer)
let priceVisibility = Product.visibility(for: \.price)

2. Protocol-Based Approach (For Multiple Entities) #

If you need this visibility logic across multiple CoreData entities, a protocol lets you standardize the pattern while keeping each entity’s rules separate.

First, define the protocol:

protocol AttributeVisibilityProvider {
    associatedtype Visibility: RawRepresentable where Visibility.RawValue == String
    static func visibility(for attribute: String) -> Visibility?
}

Then have your Product entity conform to it:

extension Product: AttributeVisibilityProvider {
    enum Visibility: String {
        case `public`
        case `private`
    }

    static func visibility(for attribute: String) -> Visibility? {
        // Use a dictionary for cleaner lookup if you have many attributes
        let visibilityMap: [String: Visibility] = [
            #keyPath(Product.name): .public,
            #keyPath(Product.price): .private
        ]
        return visibilityMap[attribute]
    }
}

You can repeat this pattern for other entities (e.g., User, Order) by having them conform to AttributeVisibilityProvider and define their own Visibility enum and mapping.

Key Notes to Remember #

• Don’t store the enum in CoreData: Since the visibility rule is fixed per entity attribute, maintaining it in code is more flexible—you can update rules without data migrations.
• Prioritize type safety: Using KeyPath instead of raw strings reduces the chance of typos breaking your logic.
• Keep logic organized: Grouping the enum and lookup function in an entity extension keeps your codebase clean and ensures visibility rules stay tied to the entity they apply to.

Your initial idea of a returnShareableAttribute(...) function is exactly the right direction—just implement it as a static method on your CoreData entities, and you’re good to go!

内容的提问来源于stack exchange，提问作者Patrick Miron