Arrow

Reason - Example - Installation

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

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

Try it

Arrow is part of freshOS iOS toolset. Try it in an example App! Download Starter Project

How

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

Why use Arrow

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

The Swift Package Manager (SPM) is now the official way to install Arrow. The other package managers are now deprecated as of 5.1.2 and won't be supported in future versions.

Swift Package Manager

Xcode > File > Swift Packages > Add Package Dependency... > Paste https://github.com/freshOS/Arrow

Carthage - Deprecated

github "freshOS/Arrow"

CocoaPods - Deprecated

target 'MyApp'
pod 'Arrow'
use_frameworks!

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"]

Date Parsing

Globally

// Configure Global Date Parsing with one of those
Arrow.setDateFormat("yyyy-MM-dd'T'HH:mm:ssZZZZZ")
Arrow.setUseTimeIntervalSinceReferenceDate(true)
Arrow.setDateFormatter(aDateFormatter)

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

On a per-key basis

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

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
    }
}

Swift Version

Swift 2 -> version 2.0.3
Swift 3 -> version 3.0.5
Swift 4 -> version 4.0.0
Swift 4.1 -> version 4.1.0
Swift 4.2 -> version 4.2.0
Swift 5.0 -> version 5.0.0
Swift 5.1 -> version 5.1.0
Swift 5.1.3 -> version 5.1.1
Swift 5.3 -> version 6.0.0

Acknowledgements

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

Backers

Like the project? Offer coffee or support us with a monthly donation and help us continue our activities :)

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