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.
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 {
var objID: Int?
var streetAddress: String?
var city: String?
var state: String?
var postalCode: String?
init() {
}
}
struct User {
var objID: Int?
var firstName: String?
var lastName: String?
var age: Int?
var 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 {
var objID: Int?
var streetAddress: String?
var city: String?
var state: String?
var postalCode: String?
init() {
}
init(_ decoder: JSONDecoder) {
objID = decoder["id"].integer
streetAddress = decoder["street_address"].string
city = decoder["city"].string
state = decoder["state"].string
postalCode = decoder["postal_code"].string
}
}
struct User : JSONJoy {
var objID: Int?
var firstName: String?
var lastName: String?
var age: Int?
var address: Address?
init() {
}
init(_ decoder: JSONDecoder) {
objID = decoder["id"].integer
firstName = decoder["first_name"].string
lastName = decoder["last_name"].string
age = decoder["age"].integer
address = Address(decoder["address"])
}
}Then when we get the JSON back:
var user = User(JSONDecoder(data))
println("city is: \(user.address!.city!)")
//That's it! The object has all the appropriate properties mapped.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"].string
//firstName is nil, but no crashing!There is two ways to access Arrays and Dictionary. The first is the convenience methods.
{
"scopes" : ["Bakersfield", "California", "USA"]
}Now for the Swift object.
struct Scopes : JSONJoy {
var scopes: Array<String>?
init() {
}
init(_ decoder: JSONDecoder) {
decoder.getArray(&scopes) //pass the optional array by reference, it will be allocated if it is not and filled
}
} The second option is useful for embedded objects.
{
"addresses": [
{
"id": 1
"street_address": "2nd Street",
"city": "Bakersfield",
"state": "CA",
"postal_code": 93309
},
{
"id": 2
"street_address": "2nd Street",
"city": "Dallas",
"state": "TX",
"postal_code": 12345
}]
}struct Addresses : JSONJoy {
var addresses: Array<Address>?
init() {
}
init(_ decoder: JSONDecoder) {
//we check if the array is valid then alloc our array and loop through it, creating the new address objects.
if let addrs = decoder["addresses"].array {
addresses = Array<Address>()
for addrDecoder in addrs {
addresses.append(Address(addrDecoder))
}
}
}
} This can be combined with SwiftHTTP to make API interaction really clean and easy.
https://github.com/daltoniam/SwiftHTTP#clientserver-example
JSONJoy requires at least iOS 7/OSX 10.10 or above.
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.
- Complete Docs
- Add Unit Tests
- Add Example Project
- Add Rouge Installation Docs
JSONJoy is licensed under the Apache v2 License.