Argo extension example

argo-enxtenison.swift

import Argo

let json = [
    "urlString": "http://www.example.com",
    "timestamp": 1433132865,
    "date": "20150525",
    "intString": "12345",
]

struct ExampleModel {
    let urlFromString: NSURL
    let dateFromTimeStamp: NSDate
    let dateFromStringWithFormat: NSDate
    let intFromString: Int
}

let model: ExampleModel? = decode(json)

extension ExampleModel: Decodable {
    static func create(urlFromString: NSURL)(dateFromTimeStamp: NSDate)(dateFromStringWithFormat: NSDate)(intFromString: Int) -> ExampleModel {
        return ExampleModel(urlFromString: urlFromString, dateFromTimeStamp: dateFromTimeStamp, dateFromStringWithFormat: dateFromStringWithFormat, intFromString: intFromString)
    }

    static func decode(j: JSON) -> Decoded<ExampleModel> {
        return ExampleModel.create
          <^> j <| "urlString"
          <*> (j <| "timestamp" >>- toNSDate)
          <*> (j <| "date" >>- toNSDate("yyyyMMdd"))
          <*> (j <| "intString" >>- toInt)
// use parentheses to make sure the order of execution
//          <^> j <| "urlString"
//          <*> ((j <| "timestamp") >>- toNSDate)
//          <*> ((j <| "date") >>- toNSDate("yyyyMMdd"))
//          <*> ((j <| "intString") >>- toInt)
    }
}

public func toNSDate(format: String)(dateString: String) -> Decoded<NSDate> {
    return .fromOptional(NSDate.dateFromString(dateString, format: format))
}

public func toNSDate(#fromTimeStamp: NSTimeInterval) -> Decoded<NSDate> {
    return pure(NSDate(timeIntervalSince1970: fromTimeStamp))
}

public func toInt(string: String) -> Decoded<Int> {
    return .fromOptional(string.toInt())
}

extension NSURL: Decodable {
    public static func decode(j: JSON) -> Decoded<NSURL> {
        switch(j) {
        case let .String(s): return .fromOptional(NSURL(string: s))
        default: return .TypeMismatch("\(j) is not a NSURL.")
        }
    }
}

extension NSDate {
    public class func dateFromString(string: String, format: String) -> NSDate? {
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = format
        return dateFormatter.dateFromString(string)
    }
}