Arrow 🏹 - Elegant JSON Parsing in Swift

Reason - Example - Installation

identifier <-- json["id"]
name <-- json["name"]
stats <-- json["stats"]

Reason

Why

Because parsing JSON in Swift is full of unecessary if lets, obvious casts and nil-checks
There must be a better way

How

By using a simple arrow operator that takes care of the boilerplate code for us.
Json mapping code becomes concise and maintainable ❤️

What

Simple & Lightweight (~200lines)
Pure Swift
Leaves your models clean
Implicitly casts JSON values to the right types in your model
Automatic NSDate, NSURL, Enum, Custom model Parsing
Converts string values to numeric types in your model
Does not crash if JSON key is not there, nor returns nil, it simply doesn't do anything
No overly complex obscure functional chaining operator overloading voodoo magic ?==:>>><> 😅

Example

Swift Model

struct Profile {
    var identifier = 0
    var name = ""
    var link:NSURL?
    var weekday:WeekDay = .Monday
    var stats = Stats()
    var phoneNumbers = [PhoneNumber]()
}

JSON File

{
    "id": 15678,
    "name": "John Doe",
    "link": "https://apple.com/steve",
    "weekdayInt" : 3,
    "stats": {
        "numberOfFriends": 163,
        "numberOfFans": 10987
    },
    "phoneNumbers": [{
                     "label": "house",
                     "number": "9809876545"
                     }, {
                     "label": "cell",
                     "number": "0908070656"
                     }, {
                     "label": "work",
                     "number": "0916570656"
    }]
}

Before (Chaos)

var profile = Profile()

// Int
if let id = json["id"] as? Int {
    profile.identifier = id
}  
// String
if let name = json["name"] as? String {
    profile.name = name
}
// NSURL
if let link = json["link"] as? String, url = NSURL(string:link)  {
    profile.link = link
}
// Enum
if let weekdayInt = json["weekdayInt"] as? Int, weekday = WeekDay(rawValue:weekdayInt) {
    profile.weekday = weekday
}
// Custom nested object
if let statsJson = json["stats"] as? AnyObject {
    if let numberOfFans = statsJson["numberOfFans"] as? Int {
        profile.stats.numberOfFans = numberOfFans
    }
    if let numberOfFriends = statsJson["numberOfFriends"] as? Int {
        profile.stats.numberOfFriends = numberOfFriends
    }
}
// Array of custom nested object
if let pns = json["phoneNumbers"] as? [AnyObject] {
    for pn in pns {
        phoneNumbers.append(PhoneNumber(json: pn))
    }
}

After 🎉🎉🎉

extension Profile:ArrowParsable {
    mutating func deserialize(json: JSON) {
        identifier <-- json["id"]
        link <-- json["link"]
        name <-- json["name"]
        weekday <-- json["weekdayInt"]
        stats <- json["stats"]
        phoneNumbers <-- json["phoneNumbers"]
    }
}

Usage

let profile = Profile()
profile.deserialize(json)

Installation

Carthage

github "freshOS/Arrow"

CocoaPods

pod 'Arrow'
use_frameworks!

Manually

Simply Copy and Paste Arrow.swift in your Xcode Project :) https://github.com/freshOS/Arrow/blob/master/Arrow.swift

As A Framework

Grab this repository and build the Framework target on the example project. Then Link against this framework.

How Does That Work

Notice earlier we typed :

stats <-- json["stats"]

That's because we created and extension "Stats+Arrow.swift" enabling us to use the Arrow Operator

//  Stats+Arrow.swift

import Foundation

extension Stats:ArrowParsable {
    mutating func deserialize(json: JSON) {
        numberOfFriends <-- json["numberOfFriends"]
        numberOfFans <-- json["numberOfFans"]
    }
}

Flexible you said

DO I have to use the <-- for my sub models
Nope, you could write it like so if you wanted :

stats.numberOfFriends <-- json["stats.numberOfFriends"]
stats.numberOfFans <-- json["stats.numberOfFans"]

Hey I don't want to parse NSDates in every files, do you have something for me?

Sure, just set your date format once and you're done.

// Configure NSDate Parsing
Arrow.setDateFormat("yyyy-MM-dd'T'HH:mm:ssZZZZZ")
Arrow.setUseTimeIntervalSinceReferenceDate(true)

// Dates can be parsed form custom date format or timestamp
let json:JSON = JSON(["date": "2013-06-07T16:38:40+02:00", "timestamp": 392308720])
date1 <-- json["date"]
date2 <-- json["timestamp"]

What if I want a Custom NSDate format for a specific key ?

createdAt <-- json["created_at"]?.dateFormat("yyyy-MM-dd'T'HH:mm:ssZZZZZ")

Just provide it on a case per case basis ! 🎉

Accessing JSON values

Nested values

value <-- json["nested.nested.nested.nestedValue"]

Object at index

value <-- json[12]

Combine both

value <-- json[1]?["someKey"]?[2]?["something.other"]

Looping on Array

if let collection = json.collection {
    for jsonEntry in collection {
        //Do something
    }
}

Acknoledgments

This wouldn't exist without YannickDot, Damien-nd and maxkonovalov

Other repos ❤️

Arrow is part of a series of lightweight libraries aiming to make developing iOS Apps a breeze :

Layout : Stevia
Async code : then
JSON WebServices : ws

viktorgardart/Arrow