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iOS Build a Simple iPhone App with Swift 2.0 Getting Started with iOS Development Architecture of an iOS App

Posted by Øyvind Stokke-Zahl
Øyvind Stokke-Zahl
3,169 Points

Won't compile

In the code challenge (Swift Recap Pt 1) I get a compiler error on this code:

struct Tag {
    let name: String
}

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

    init(title: String, author: String, tag: String) {
        self.title = title
        self.author = author
        self.tag = Tag(name: tag)
    }

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

let firstPost = Post(title: "iOSDevelopment", author: "Apple", tag: "swift")
let postDescription = firstPost.description()

But in Xcode I get no errors, and when I open Preview to see the error, it's empty. What am I doing wrong?

3 Answers

Kyler Smith
Kyler Smith
10,110 Points
Kyler Smith
Kyler Smith
10,110 Points

Very close! Here is how I did it. I skipped the init method and declared the Tag name in the parameter for the firstPost.

struct Tag {
    let name: String
}

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

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

let firstPost = Post(title: "aTitlte", author: "anAuthor", tag: Tag(name: "aTag"))
let postDescription = firstPost.description()
Øyvind Stokke-Zahl
Øyvind Stokke-Zahl
3,169 Points

Perfect. Thanks!

Kyler Smith
Kyler Smith
10,110 Points
Kyler Smith
Kyler Smith
10,110 Points

Boris Likhobabin,

You are still giving tag a name, just inside the parameters of the Post instance. You could do the same thing and put the tag instance on a separate line as is below. They both accomplish the same thing.

// two lines
let swiftTag = Tag(name: "swift")
let firstPost = Post(title: "iOSDevelopment", author: "Apple", tag: swiftTag)
// one line
let secondPost = Post(title: "iOSDevelopment", author: "Apple", tag: Tag(name: "swift"))
Ryan Doyle
Ryan Doyle
8,587 Points
Ryan Doyle
Ryan Doyle
8,587 Points

I think maybe Xcode thinks it's fine, but the challenge wants it without the init method since it's a struct and wants you to rely on the member wise init.

Boris Likhobabin
Boris Likhobabin
3,581 Points
Boris Likhobabin
Boris Likhobabin
3,581 Points

Kyler, could you please explain to me this: let firstPost = Post(title: "aTitlte", author: "anAuthor", tag: Tag(name: "aTag")) by doing this you create an instance of a Tag right in brackets without giving it a name! Hoe so? Is this allowed?

Thanks