Arrow 🏹

Elegant JSON Parsing in Swift

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

Before

if let id = json["id"] as? Int {
  identifier = id
}
if let n = json["name"] as? String {
  name = n
}
if let s = Stats(json:json) {
  stats = s
}

After

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

🎉🎉🎉

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 (~50lines)
Pure Swift
Leaves your models clean
Implicitly casts JSON values to the right types in your model
Does not crash if JSON key is not there, nor returns nil, it simply doesn't do anything
NSDate Parsing
No overly complex obscure functional chaining operator overloading voodoo magic ?==:>>><> 😅

Installation

Using Carthage

github "s4cha/Arrow"

Manually

Simply Copy and Paste Arrow.swift in your Xcode Project :) https://github.com/s4cha/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.

Show me the code

Swift Model

struct Profile {
    var identifier = 0
    var name = ""
    var stats = Stats()
}

JSON File

{
    "id": 15678,
    "name": "John Doe",
    "stats": {
        "numberOfFriends": 163,
        "numberOfFans": 10987
    }
}

Usual Swift JSON Parsing (Chaos)

var profile = Profile()
if let id = json["id"] as? Int {
    profile.identifier = id
}  
if let name = json["name"] as? String {
    profile.name = name
}
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
    }
}

With Arrow --> Sanity preserved

extension Profile:ArrowParsable {
    init(json: JSON) {
        identifier <-- json["id"]
        name <-- json["name"]
        stats <== json["stats"]
    }
}

Integration

Step 1 - Copy paste Arrow.swift in your Xcode Project
Step 2 - Create you model parsing extension like so : "Profile+Arrow.swift"

// Profile+Arrow.swift
extension Profile:ArrowParsable {
    init(json: JSON) {
        identifier <-- json["id"]
        name <-- json["name"]
        stats <== json["stats"]
    }
}

Step 3 - Use it:

let profile = Profile(json: json)

Step 4 - Ther is no step 4

How Does that work

<-- Arrow Operator is for all Swift Types : Int.. Double .. String .. NSDate etc
<== Thick Arrow Operator is for your own custom models

Notice earlier we typed :

stats <== json["stats"]

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

//  Stats+Arrow.swift

import Foundation

extension Stats:ArrowParsable {
    init(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.valueForKeyPath("stats.numberOfFriends")
stats.numberOfFans <-- json.valueForKeyPath("stats.numberOfFans")

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

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

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

Acknoledgments

This wouldn't exist without YannickDot (https://github.com/YannickDot) and Damien-nd (https://github.com/damien-nd) <3

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

aciidgh / Arrow