GHCalls-refactor1.swift

protocol JSONMappable {
    init(json: JSON)
}

struct GHUser: JSONMappable {
    var login: String
    var id: String

    init(json: JSON) {
        self.login = json["login"].stringValue
        self.id = json["id"].stringValue
    }
}

struct GHRepository: JSONMappable {
    var id: String
    var name: String
    
    init(json: JSON) {
        self.name = json["name"].stringValue
        self.id = json["id"].stringValue
    }
}

GHSearchableWebServices.swift

class SearchableWebService<T: JSONMappable> {
    typealias SearchResponseHandler = (([T]) -> Void)
    func searchURL(withTerm term: String) -> URL {
        fatalError()
    }
    func search(term: String, handler: SearchResponseHandler? = nil) {
        let url = self.searchURL(withTerm: term)
        let task = URLSession.shared.dataTask(with: url) { data, _ , _ in
            if let data = data {
                let json = JSON(data: data)
                handler?(json["items"].arrayValue.map(T.init))
            }
        }
        task.resume()
    }
}

class GHRepositoryWebService: SearchableWebService<GHRepository> {
    override func searchURL(withTerm term: String) -> URL {
        return URL(string:"https://api.github.com/search/repositories?q=\(term)")!
    }
}

class GHUserWebService: SearchableWebService<GHUser> {
    override func searchURL(withTerm term: String) -> URL {
        return URL(string:"https://api.github.com/search/users?q=\(term)")!
    }
}