checking_type.swift

class Media {
    var url: String
    
    init(url: String) {
        self.url = url
    }
    
}

class Video: Media {
    var thumb: String
    
    init(url: String, thumb: String) {
        self.thumb = thumb
        super.init(url: url)
    }
    
}

let media: Media = Video(url: "http://[email protected]", thumb: "http://[email protected]")

print("Media is Video? \(media is Video)")