Hi, I just checked the following code at xCode 9 and swift 4 and it works fine, the page says I have errors.

Hi Juan Carlos,

I think this might be a bug in the challenge. What you're doing in your code is perfectly valid as far as I can see. The reason the code challenge is failing is that it wants you to pass a Tag instance into the init method, rather than a string that you then use to create the tag. Frankly... I like your implementation, at least as a convenience initializer. I think it makes sense to have an initializer that takes a tag instance (like the challenge wants), since in a real application, you would probably create tags separately, but that's just my opinion. There's certainly a case to be made that you would want to create tags on the fly (maybe adding some additional logic to see if the tag exists before creating it, but still).

Paging Pasan Premaratne: am I missing any reason why Juan Carlos's code shouldn't pass?

For now, here's how to make the challenge happy:

struct Tag {
    let name: String
}

struct Post {
    var title : String
    var author : String
    var tag : Tag

    init(title: String, author: String, tag: Tag)  // use a Tag instance as a parameter
    {
        self.title = title
        self.author = author
        self.tag = tag  // no initialization needed here
    }

    func description () -> String {
        return "\(title) by \(author). Filed under \(tag.name)"
    }
}

// I'm creating the tag inline. Alternatively, you could create a constant and then pass that in.
let firstPost = Post(title : "iOS Development", author: "Apple", tag: Tag(name: "swift"))
let postDescription = firstPost.description()

Hope this makes sense!

Cheers

-Greg