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iOS Build an Interactive Story App with Swift 2 Creating the User Interface Programmatically Prepare For Segue

Cannot assign value of type '(String) -> Page' to type 'Page'

Within the prepareForSegue function, I am getting an error as I try to assign the constant pageController.page to Adventure.story. I am a bit confused as to why, hoping someone can help me figure this out! Thanks!

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "startAdventure" {
            if let pageController = segue.destinationViewController as? PageController {
                pageController.page = Adventure.story


class Page {
    let story: Story

    typealias Choice = (title: String, page: Page)

    var firstChoice: Choice?
    var secondChoice: Choice?

    init(story: Story) {
        self.story = story

extension Page {
    func addChoice (title: String, story: Story) -> Page {
        let page = Page(story: story)
        return addChoice(title, page: page)

    func addChoice (title: String, page: Page) -> Page {
        switch (firstChoice, secondChoice) {
            case (.Some, .Some) : break
            case (.None, .None), (.None, .Some) :
                firstChoice = (title, page)
            case (.Some, .None) :
                secondChoice = (title, page)
        return page

struct Adventure {
    static func story(name: String) -> Page { //Static readonly computed property prevents against story being changed
        let returnTrip = Page(story: .ReturnTrip)
        let touchdown = returnTrip.addChoice("Stop and Investigate", story: .TouchDown)
        let homeward = returnTrip.addChoice("Continue Home to Earth", story: .Homeward)
        let rover = touchdown.addChoice("Explore the Rover", story: .Rover)
        let crate = touchdown.addChoice("Open the Crate", story: .Crate)

        homeward.addChoice("Head back to Mars", page: touchdown)
        let home = homeward.addChoice("Continue Home to Earth", story: .Home)

        let cave = rover.addChoice("Explore the Coordinates", story: .Cave)
        rover.addChoice("Return to Earth", page: home)

        cave.addChoice("Continue towards faint light", story: .Droid)
        cave.addChoice("Refill the ship and explore the rover", page: rover)

        crate.addChoice("Explore the Rover", page: rover)
        crate.addChoice("Use the key", story: .Monster)

        return returnTrip

1 Answer

Hi Kyle, You are missing small part, the line in your prepareForSegue should read: pageController.page = Adventure.story(name)

Please note that Adventure.story is a function that takes a String and returns a Page object, it is defined like this in your code above: static func story(name: String) -> Page {..} So you have to give it the String which represent the story name, and receive back the Page object that will be displayed in the PageController.

I hope this helps. Cheers, Safwat