How do you make a Viewable? about viewer HOT 1 CLOSED

class Photo: Viewable {
    var placeholder = UIImage("some-placeholder")
    var type: ViewableType = .image
    var url: String? // set your URL here
    var assetID: String?

    func media(_ completion: @escaping (_ image: UIImage?, _ error: NSError?) -> Void) {

        // download the photo and return it
    }
}