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iOS Build a Simple iPhone App with Swift 2.0 Getting Started with iOS Development Swift Recap Part 1

Vi Phung
Vi Phung
2,915 Points
Posted by Vi Phung
Vi Phung
2,915 Points

Hi, treeHouse team, I've got an error - "Make sure you're declaring an instance method that returns a string."

// Below is my code...

struct Tag {
    let name: String

}

// creating Struct named Post...
struct Post {
    // adding three stored properties...
    let title: String
    let author: String
    let tag: Tag

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

    // adding instance method, no param..return a String
    func description() ->String {
        let description = "\(title) by \(author). Filed under \(tag)"
        return description
    }
}

// Creating an instance of Post = let firstPost...
let someTag = Tag(name: "swift")
let firstPost = Post(title: "iOSDevelopment", author: "Apple", tag: someTag)

let postDescription = firstPost.description()

// I can't find the error.??? please help!

structs.swift 
struct Tag {
    let name: String
}

// creating Struct named Post...
struct Post {
    // adding three stored properties...
    let title: String
    let author: String
    let tag: Tag

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

    // adding instance method, no param..return a String
    func description() ->String {
        let description = "\(title) by \(author). Filed under \(tag)"
        return description
    }
}

// Creating an instance of Post = let firstPost...
let someTag = Tag(name: "swift")
let firstPost = Post(title: "iOSDevelopment", author: "Apple", tag: someTag)
let postDescription = firstPost.description()

4 Answers

Steve Hunter
Steve Hunter
57,712 Points

There are some silly spacing issues in there around the String return from the description function. I don't think that is syntactically incorrect, so I think that's just the compiler being extra picky.

This code works:

struct Post {
    // adding three stored properties...
    let title: String
    let author: String
    let tag: Tag

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

    // adding instance method, no param..return a String
    func description() -> String {    // space after the arrow, before the 'S'
        return "\(title) by \(author). Filed under \(tag.name)"
    }
}

let firstPost = Post(title: "iOS Development", author: "Apple", tag: Tag(name: "swift"))
let postDescription = firstPost.description()
Steve Hunter
Steve Hunter
57,712 Points

Yes, it is requiring a space between the arrow and the word String. Without it the above code fails, with it, it passes. I've added a comment in the code.

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi there,

You want to output tag.name in the string interpolation; not just the Tag instance:

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

I also returned the string directly rather than creating a temporary constant holder for it first.

Steve.

Steve Hunter
Steve Hunter
57,712 Points

You can also create the Tag instance inside creating the Post instance:

let firstPost = Post(title: "iOS Development", author: "Apple", tag: Tag(name: "swift"))
let postDescription = firstPost.description()

I hope that helps,

Steve.

Vi Phung
Vi Phung
2,915 Points
Vi Phung
Vi Phung
2,915 Points

Thank you Steve, that's very helpful. I didn't know you can access the member wise initialiser method using dot syntax in string interpolation.

Vi.

Steve Hunter
Steve Hunter
57,712 Points

Hi Vi,

You're just accessing the stored property of the Tag instance. Inside the Post instance, there's an instance of Tag called, imaginatively, tag. You can access the stored properties of that instance the same way you can anywhere. So, you can interpolate tag.name as that's just another variable/constant that can be included within the output string.

Steve.

Vi Phung
Vi Phung
2,915 Points
Vi Phung
Vi Phung
2,915 Points

I've just submitted the new codes but the error still persist. It's the same error??? I've tried the new codes in swift playground and it works perfectly. Not sure what's happening here...

Steve Hunter
Steve Hunter
57,712 Points

Playgrounds don't know what you are trying to pass - they just check general syntax, not the challenge output. Let me try the code ... be right back ...

Vi Phung
Vi Phung
2,915 Points
Vi Phung
Vi Phung
2,915 Points

Yes, it works! Thank you for your help Steve. I've been scratching my head on this for more than a couple of hours. Now I know what coding style this console accepts. I guess I'm just too lazy to add a spaceBar there lol. Thank you again and have a good day.

Steve Hunter
Steve Hunter
57,712 Points

Glad you got it sorted. :smile: