Protocol implementations or enum with associated values with SwiftData?

Using Swift
1

I'm creating an app using SwiftData with two models: Item and Detail, where an Item stores an array of Detail objects.

A Detail can represent different kinds of mutually exclusive data, for example:

  • text
  • date
  • location
  • etc

Each type also has different SwiftUI views for creating, editing, and displaying the value.

I'm new to Swift and SwiftUI, so I'm not sure what the pragmatic approach is for implementing these different types.

My first idea was defining a protocol with an associatedtype and separate model implementations per value type:

protocol Detail {
    associatedtype ValueType

    var name: String { get set }
    var value: ValueType { get set }
    var forDisplay: String { get }
}

@Model
final class TextDetail: Detail {
    var name: String
    var value: String

    var forDisplay: String {
        value
    }

    init(name: String, value: String) {
        self.name = name
        self.value = value
    }
}

@Model
final class DateDetail: Detail {
    var name: String
    var value: Date
    
    var forDisplay: String {
        value.formatted()
    }
    
    init(name: String, value: Date) {
        self.name = name
        self.value = value
    }
}

However, this doesn't enforce exhaustiveness, and it feels rather verbose when the implementations don't differ that much.

The other approach I thought of was using an enum with associated values as the data type:

enum DetailValue {
    case text(String)
    case date(Date)

    var forDisplay: String {
        switch self {
        case .text(let text):
            text
        case .date(let date):
            date.formatted()
        }
    }
}

@Model
final class Detail {
    var name: String
    var value: DetailValue

    init(name: String, value: DetailValue) {
        self.name = name
        self.value = value
    }
}

Though, I'm unsure whether SwiftData handles this well.

I'd highly appreciate suggestions, thanks :)

3

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