Generic Class with Enum with associated values

Question

I'm trying to create a generic UITableViewCell that inherits from an enum with associated values.
This is what I tried:

Enum declaration:

enum Content: Equatable  {
    case text(String)
    case image(UIImage)
    case error(Error)
    case indicator
}

And UITableViewCell declaration:

class MessageTableViewCell<T: Content>: UITableViewCell {
    var content: T?
}

But it fails with:

Type 'T' constrained to non-protocol, non-class type 'Content'

I'm trying to set up my cell with different types of "content view," depending on its content. Do note: I'm using XIB for the interface of the cell, so subclassing is not possible (I think). Any advice will be highly appreciated!

Can you clarify why you are trying to use generics versus just defining the `content` property with a type of `Content`? — HangarRash, Apr 02 '23 at 20:26

score 2 · Accepted Answer · answered Apr 02 '23 at 22:49

As per the error, you need to constrain it to either a protocol or a class. You can try the below code.

enum Content  {
    case text(String)
    case image(UIImage)
    case error(Error)
    case indicator
}

protocol CellContent {
    var content: Content { get set }
}

class MessageTableViewCell<T: CellContent>: UITableViewCell {
    var content: T?
}

Generic Class with Enum with associated values

1 Answers1