class MyViewController: UIViewController, InputRequiring {

    typealias InputType = MyType

    override func viewDidLoad() {
        super.viewDidLoad()
        // StoryFlow provides 'input' that was produced as an 'output' by previous vc
        title = input.description
    }
}

class JustViewController: UIViewController, InputRequiring {

    // When vc doesn't require any input it should still declare it's 'InputType'.
    // Otherwise it's impossible for this vc to be opened using StoryFlow.
    struct InputType {}
}

Also there's a convenience initializer designed to make InputRequiring vcs easy.

extension InputRequiring {
    init(input: InputType) { ✨ }
}

// Example
let myType = MyType()
let myVc = MyViewController(input: myType)
myVc.input // myType

class MyViewController: UIViewController, OutputProducing {

    typealias OutputType = MyType

    @IBAction func goToNextVc() {
        // StoryFlow will go back to a vc in the nav stack with `UpdateType = MyType`
	// Or it will create, inject and show a new vc with `InputType = MyType`
        produce(MyType())
    }
}

To produce more than one type of output see the section about OneOfN enum.

Also there's a convenience initializer designed to make OutputProducing vcs easy.

extension OutputProducing {
    init(produce: @escaping (OutputType) -> ()) { ✨ }
}

// Example
let myType = MyType
let myVc = MyViewController(produce: { output in
    output == myType // true
})
myVc.produce(myType)

class UpdatableViewController: UIViewController, UpdateHandling {

    func handle(update: MyType) {
        // Do something ✨
        // This gets called when a presented vc produces an output of `OutputType = MyType`
    }
}

To handle more than one type of output see the section about OneOfN enum.

class ZooViewController: UIViewController, IOU {
    
    // 'OneOfN' with 'InputRequiring'
    typealias InputType = OneOf2<Jungle, City>

    override func viewDidLoad() {
        super.viewDidLoad()
	// Just use the 't1'...'tN' enum cases
	switch input {
	case .t1(let jungle):
	    title = jungle.name
	case .t2(let city):
	    title = city.countryName
	}
    }
    
    // 'OneOfN' with 'OutputProducing'
    typealias OutputType = OneOf8<Tiger, Lion, Panda, Koala, Fox, Dog, Cat, OneOf2<Pig, Cow>>
    
    @IBAction func openRandomGate() {
        // There are a few ways 'produce' can be called with 'OneOfN' type
	switch Int.random(in: 1...9) {
        case 1: produce(.t1(🐯)) // Use 't1' enum case to wrap 'Tiger' type
        case 2: produce(.value(🦁)) // Use convenience 'value' to wrap 'Lion' to 't2' case
        case 3: produce(🐼) // Use directly with 'Panda' type
        case 4: produce(🐨)
        case 5: produce(🦊)
        case 6: produce(🐶)
        case 7: produce(🐱)
        case 8: produce(.t8(.t1(🐷))) // Use 't8' and 't1' enum cases to double wrap it
        case 9: produce(.value(🐮)) // Use 'value' to wrap it only once
	}
    }
    
    // 'OneOfN' with 'UpdateHandling'
    typealias UpdateType = OneOf3<Day, Night, Holiday>
    
    func handle(update: UpdateType) {
	// Just use the 't1'...'tN' enum cases
	switch input {
	case .t1(let day):
	    subtitle = "Opened during \(day.openHours)"
	case .t2(let night):
	    subtitle = "Closed for \(night.sleepHours)"
	    openRandomGate() // 🙈
	case .t3(let holiday):
	    subtitle = "Discounts on \(holiday.dates)"
	}
    }
}