Sample Swift JSON Parsing

ParsingExtensions.swift

// *** Extensions
extension NSString {
	func dictionaryFromJson() -> NSDictionary {
		let jsonData = self.dataUsingEncoding( NSUTF8StringEncoding )!
		return jsonData.dictionary()
	}
}
extension String {
	func dictionaryFromJson() -> NSDictionary {
		let jsonData = self.dataUsingEncoding( NSUTF8StringEncoding )!
		return jsonData.dictionary()
	}
}
extension NSData {
	func dictionary() -> NSDictionary {
		var error : NSError?
		return NSJSONSerialization.JSONObjectWithData( self, options: NSJSONReadingOptions.MutableContainers, error: &error ) as NSDictionary
	}
	// quick test function for downloading remote data
	class func getJsonDataFromURL( url : String ) -> NSData {
		return NSData( contentsOfURL: NSURL( string : url ) )
	}
	class func getJsonDataFromUrlAsync( url: String, completion: ( ( dict: NSDictionary, error: NSError? ) -> () ) ) {
		let request = NSURLRequest(URL: NSURL( string: url )! )
		NSURLConnection.sendAsynchronousRequest( request, queue: NSOperationQueue.mainQueue(), completionHandler: {(response: NSURLResponse!,data: NSData!,error: NSError!) -> Void in
			if let error = error { completion( dict: NSDictionary(), error: error ); return }
			completion( dict: data.dictionary(), error: nil )
		})
	}
}

extension NSDictionary {
	/// Returns a "safe" value cast to the type of the fallback condition.
	/// If the key ( or value ) are missing, then it returns the "or"
	/// let mystr = mydict.safe( "testKey", or: "Default Value" )
	func safe<T>( forKey: String, or: T ) -> T {
		return self[ forKey ] as? T ?? or
	}
}

SampleUsage.swift

// *** Sample Usage
let jsonString : NSString = ( "{\"id\":34, \"name\":\"John\", \"email\":\"[email protected]\"}" as NSString )
let mydata : Dictionary = jsonString.dictionaryFromJson()
let myuser : UserModel = UserModel( mydata )

UserModel.swift

// *** Sample Model Class
public struct UserModel {
	public var id
	public var name
	public var email
	public var missing
	
	init( fromDictionary d : NSDictionary ) {
		id = d.safe( "id", or: 0 )
		name = d.safe( "name", or: "" )
		email = d.safe( "email", or: "" )
		missingItem = d.safe( "missing", or: "" )
	}
}

// MARK: - Printable Extension

extension UserModel : Printable {
	// allows us to just use println( myuser )
	public var description : String {
		return "USER ID \(self.id) : \(self.name) : \(self.email)"
	}
}

// MARK: - Equatable Extension

extension UserModel : Equatable {}
public func ==( lhs : UserModel, rhs : UserModel ) -> Bool {
	return lhs.id == rhs.id && lhs.name == rhs.name && lhs.email == rhs.email
}