UIKonf 2017 – Day 2 – Chris Eidhof & FlorianKugler – Intermediate Types

IntermediateTypes.swift

struct KeyboardWillShowPayload {
    let endFrame: CGRect

    init(userInfo: [AnyHashable: Any]) {
        endFrame = userInfo[UIKeyboardFrameEndUserInfoKey] as! CGRect
    }
}


struct NotificationDescriptor<A> {
    let name: Notification.Name
    let parse: ([AnyHashable: Any]) -> A
}

let keyboardWillShow = NotificationDescriptor(name: .UIKeyboardWillShow, parse: KeyboardWillShowPayload.init)


extension NotificationCenter {
    @discardableResult
    func addObserver<A>(for descriptor: NotificationDescriptor<A>, object obj: Any?, queue: OperationQueue?, using block: @escaping (A) -> Void) -> NSObjectProtocol {
        return addObserver(forName: descriptor.name, object: obj, queue: queue, using: { (note) in
            block(descriptor.parse(note.userInfo!))
        })
    }
}

class ViewController: UIViewController {
    @IBOutlet weak var bottomLayoutConstrait: NSLayoutConstraint!

    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(for: keyboardWillShow, object: nil, queue: nil) { [weak self] (payload) in
            self?.bottomLayoutConstrait?.constant = payload.endFrame.height
        }
    }
}


struct Episode {

}

let url = URL(string: "http://localhost:8000/episodes.json")!

final class Webservice {
    func loadAllEpisodes(completion: @escaping ([Episode]?) -> ()) {
        let url = URL(string: "http://localhost:8000/episodes.json")!
        URLSession.shared.dataTask(with: url) { (data, _, _) in
            guard
                let data = data,
                let json = try? JSONSerialization.jsonObject(with: data),
                let dicts = json as? [JSONDictionary]
            else {
                completion(nil)
                return
            }

            let episodes = dicts.flatMap(Episode.init)
            completion(episodes)
        }.resume()
    }


    func loadEpisodeWithID(_ id: String, completion: @escaping ([Episode]?) -> ()) {
        let url = URL(string: "http://localhost:8000/episodes/\(id).json")!
        URLSession.shared.dataTask(with: url) { (data, _, _) in
            guard
                let data = data,
                let json = try? JSONSerialization.jsonObject(with: data),
                let dicts = json as? [JSONDictionary]
                else {
                    completion(nil)
                    return
            }

            let episodes = dicts.flatMap(Episode.init)
            completion(episodes)
            }.resume()
    }


    func load<A>(_ resource: Resource<A>, completion: @escaping (A?) -> ()) {
        let url = URL(string: "http://localhost:8000/episodes.json")!
        URLSession.shared.dataTask(with: url) { (data, _, _) in
            guard
                let data = data,
                let json = try? JSONSerialization.jsonObject(with: data),
            else {
                completion(nil)
                return
            }

            completion(resource.parse(json))
            }.resume()
    }

}




struct Resource<A> {
    let url: URL
    let parse: (Any) -> A?
}

let allEpisodes = Resource<[Episode]>(url: url) { (json) -> [Episode]? in
    guard let dicts = json as? [JSONDictionary] else { return nil }

    return dicts.flatMap(Episode.init)
}

func episodeResource(for id: String) -> Resource<Episode> {
    let url = URL(string: "http://localhost:8000/episodes/\(id).json")!
    return Resource<Episode>(url: url) { json in
        guard let dicts = json as? [JSONDictionary] else { return nil }
        return Episode(dictionary: dicts)
    }
}


Webservice().load(allEpisodes) { print($0) }