JSONJoy

Convert JSON to Swift objects. The Objective-C counterpart can be found here: JSONJoy.

Parsing JSON in Swift has be likened to a trip through Mordor, then JSONJoy would be using eagles for that trip.

Deprecation

The release of Swift 4 brought support for the new Codable protocol. This renders most of JSONJoy unneccessary and thus will be deprecated. Version 3.0.2 has been update to support Swift 4 as a means of backward compatibility, but I would encourage the adoption of the new Codable protocol. I wrote a post about it here

First thing is to import the framework. See the Installation instructions on how to add the framework to your project.

import JSONJoy

Example

First here is some example JSON we have to parse.

{
    "id" : 1,
    "first_name": "John",
    "last_name": "Smith",
    "age": 25,
    "address": {
        "id": 1,
        "street_address": "2nd Street",
        "city": "Bakersfield",
        "state": "CA",
        "postal_code": 93309
     }

}

We want to translate that JSON to these Swift objects:

struct Address {
    let objID: Int?
    let streetAddress: String?
    let city: String?
    let state: String?
    let postalCode: String?
    init() {

    }
}

struct User {
    let objID: Int?
    let firstName: String?
    let lastName: String?
    let age: Int?
    let address = Address()
    init() {

    }
}

Normally this would put us in a validation nightmare:

var user = User()
var error: NSError?
var response: AnyObject? = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions(), error: &error)
if let userDict = response as? NSDictionary {
    if let addressDict = userDict["address"] as? NSDictionary {
        user.address.city = addressDict["city"] as? String
        user.address.streetAddress = addressDict["street_address"] as? String
        //etc, etc
    }
    user.firstName = userDict["first_name"] as? String
    user.lastName = userDict["last_name"] as? String
    //etc, etc
}

JSONJoy makes this much simpler. We have our Swift objects implement the JSONJoy protocol:

struct Address : JSONJoy {
    let objID: Int
    let streetAddress: String
    let city: String
    let state: String
    let postalCode: String
    let streetTwo: String?

    init(_ decoder: JSONLoader) throws {
        objID = try decoder["id"].get()
        streetAddress = try decoder["street_address"].get()
        city = try decoder["city"].get()
        state = try decoder["state"].get()
        postalCode = try decoder["postal_code"].get()
        streetTwo = decoder["street_two"].getOptional()
        
        //just an example of "checking" for a property. 
        if let meta: String = decoder["meta"].getOptional() {
            print("found some meta info: \(meta)")
        }
    }
}

struct User : JSONJoy {
    let objID: Int
    let firstName: String
    let lastName: String
    let age: Int
    let address: Address
    let addresses: [Address]

    init(_ decoder: JSONLoader) throws {
        objID = try decoder["id"].get()
        firstName = try decoder["first_name"].get()
        lastName = try decoder["last_name"].get()
        age = try decoder["age"].get()
        address = try Address(decoder["address"])
        addresses = try decoder["addresses"].get() //infers the type and returns a valid array
    }
}

Then when we get the JSON back:

do {
    var user = try User(JSONLoader(data))
    println("city is: \(user.address.city)")
    //That's it! The object has all the appropriate properties mapped.
} catch {
    print("unable to parse the JSON")
}

This also has automatic optional validation like most Swift JSON libraries.

//some randomly incorrect key. This will work fine and the property will just be nil.
firstName = decoder[5]["wrongKey"]["MoreWrong"].getOptional()
//firstName is nil, but no crashing!

Custom Types

If you to extend a standard Foundation type (you probably won’t need to though)

extension UInt64:   JSONBasicType {}

SwiftHTTP

This can be combined with SwiftHTTP to make API interaction really clean and easy.

https://github.com/daltoniam/SwiftHTTP#clientserver-example

Requirements

JSONJoy requires at least iOS 7/OSX 10.10 or above.

Installation

Swift Package Manager

Add the project as a dependency to your Package.swift:

import PackageDescription

let package = Package(
    name: "YourProject",
    dependencies: [
        .Package(url: "https://github.com/daltoniam/JSONJoy-Swift", majorVersion: 3)
    ]
)

Rogue

First see the installation docs for how to install Rogue.

To install JSONJoy run the command below in the directory you created the rogue file.

rogue add https://github.com/daltoniam/JSONJoy-Swift

Next open the libs folder and add the JSONJoy.xcodeproj to your Xcode project. Once that is complete, in your “Build Phases” add the JSONJoy.framework to your “Link Binary with Libraries” phase. Make sure to add the libs folder to your .gitignore file.

Other

Simply grab the framework (either via git submodule or another package manager).

Add the JSONJoy.xcodeproj to your Xcode project. Once that is complete, in your “Build Phases” add the JSONJoy.framework to your “Link Binary with Libraries” phase.

Add Copy Frameworks Phase

If you are running this in an OSX app or on a physical iOS device you will need to make sure you add the JSONJoy.framework included in your app bundle. To do this, in Xcode, navigate to the target configuration window by clicking on the blue project icon, and selecting the application target under the “Targets” heading in the sidebar. In the tab bar at the top of that window, open the “Build Phases” panel. Expand the “Link Binary with Libraries” group, and add JSONJoy.framework. Click on the + button at the top left of the panel and select “New Copy Files Phase”. Rename this new phase to “Copy Frameworks”, set the “Destination” to “Frameworks”, and add JSONJoy.framework.

TODOs

• Add Unit Tests

License

JSONJoy is licensed under the Apache v2 License.

Contact

Dalton Cherry

• https://github.com/daltoniam
• http://twitter.com/daltoniam
• http://daltoniam.com