Swift gists

generics.swift

// Generic Types
class Carousel<T: CustomStringConvertible> {
    var items = [T]()
    var currentPosition = 0
    var count: Int {return items.count}
    var isEmpty: Bool {return items.isEmpty}

    func append(item: T) {items.append(item)}
    func next() -> T? {
        if self.isEmpty { return nil }
        let nextItem = items[currentPosition]
        currentPosition = (currentPosition + 1) % count
        return nextItem
    }
    subscript(position: Int) -> T? {
        if self.isEmpty { return nil }
        return items[position % count]
    }
}

var intCarousel = Carousel<Int>()
intCarousel.append(3)
intCarousel.append(5)

extension Carousel: CustomStringConvertible {
    public var description: String {
        return "\(self.dynamicType) has \(count) items: " + 
                items.map{return $0.description}.joinWithSeparator(",")
    }
}
print(intCarousel)

// When you don't own the class, subclass it.
class Carousel<T> {
    var items = [T]()
    var currentPosition = 0
    var count: Int {return items.count}
    var isEmpty: Bool {return items.isEmpty}

    func append(item: T) {items.append(item)}
    func next() -> T? {
        if self.isEmpty { return nil }
        let nextItem = items[currentPosition]
        currentPosition = (currentPosition + 1) % count
        return nextItem
    }
    subscript(position: Int) -> T? {
        if self.isEmpty { return nil }
        return items[position % count]
    }
}

class PrintableCarousel<T: CustomStringConvertible>: Carousel<T>, CustomStringConvertible {
    var description: String {
        var d = "\(self.dynamicType) with \(count) items: "
        for it in items {
            d += ",\(it.description)"
            print(it.description)
        }
        return d
    }
}
var intCarousel = Carousel<Int>()
intCarousel.append(3)
intCarousel.append(5)

print(intCarousel)

// Associated Types
protocol Traversable {
    typealias Element
    var count: Int {get}
    var first: Element? {get}
    var last: Element? {get}
    mutating func previous() -> Element?
    mutating func next() -> Element?
    mutating func reset()
}

extension Carousel: Traversable {
    public var first: T? {return self.isEmpty ? nil : self[0]}
    public var last: T? {return self.isEmpty ? nil : self[self.count - 1]}
    public func previous() -> T? {
        if self.isEmpty {
            return nil
        }   
            currentPosition = (currentPosition + count - 1) % self.count 
            return self[currentPosition]
    }
    public func reset() {
        currentPosition = 0
    }
}

weather.swft

import Foundation 
func weatherDataForCity(city: String, closure: (json: NSDictionary) -> ()) {
    print("weatherDataForCity")
    var urlString = "http://api.openweathermap.org/data/2.5/weather?q=" + city
    var url = NSURL(string: urlString)

    if url == nil {
        print("dead")
        return
    }
    print("sdsd")
    let task = NSURLSession.sharedSession().dataTaskWithURL(url!) { (data, response, error) in
        print("sss")
        do {
            print("task")
            let json = try NSJSONSerialization.JSONObjectWithData(data!, 
                options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
            print("json \(json)")
            // closure(json: json)
        } catch {
            print("shit")
        }
    }
    print("e")
    task.resume()
    print("d")
}

//Sample usage
weatherDataForCity("Chicago") {(json) in 
    print(json)
}