Iglistkit: IGListDiffable and Non-class type

[pgherveou]

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• [x] I have reviewed the README and documentation
• [x] I have searched existing issues and this is not a duplicate
  

  General information

Is there any reason IGListDiffable could not be implemented on Struct?
the following code returns this error:
Non-class type 'Foo' cannot conform to class protocol 'IGListDiffable'

struct Foo: IGListDiffable {
  let id: String

  func diffIdentifier() -> NSObjectProtocol {
    return id as NSObjectProtocol
  }

  func isEqual(object: Any?) -> Bool {
    return false
  }
}

• Library version(s): 1.0.0
• iOS version(s): 10.0

[jessesquires]

Thanks @pgherveou !

See the discussion in #35.

In short, this is a limitation in the Swift compiler when bridging _from_ Objective-C _to_ Swift. It's difficult (or impossible) to determine if reference semantics are required, or not. Thus, protocols are imported as @objc which requires a reference (class) type.