SpotlightIndexableArticle.swift

//Protocol for spotlight indexing
protocol SpotlightIndexable {
    var spotlightTitle: String {get}
    var spotlightDescription: String {get}
    var spotlightKeywords: [String] {get}
    var spotlightImageData: NSData? {get}
    var spotlightUrl: NSURL {get}
    func index()
}

//Object that will be indexed
struct Article {
    let title: String
    let image: UIImage?
    let text: String
    let tags: [String]
    let url: NSURL
}

//Exactly how Article will be indexed
extension Article : SpotlightIndexable{
    var spotlightTitle: String{
        return self.title
    }
    
    var spotlightDescription: String{
        return self.text
    }
    
    var spotlightKeywords: [String]{
        return self.title.words + self.text.words
    }
    
    var spotlightImageData: NSData?{
        guard let image = self.image else {return nil}
        return UIImagePNGRepresentation(image)
    }
    
    var spotlightUrl: NSURL{
        return self.url
    }
    
    func index(){
        //Code this
    }
}

//Helpers
extension String{
    var words: [String]{
        return characters.split{$0 == " "}
        .map{String($0)}.map{$0
        .stringByTrimmingCharactersInSet(NSCharacterSet
            .punctuationCharacterSet())}
    }
}

func + (lhs: [T], rhs: [T]) -> [T]{
    var array = [T]()
    array.appendContentsOf(lhs)
    array.appendContentsOf(rhs)
    return array
}