ChainingMethodsCode.swift

class APICaller {
    var url:URL?
    var method = HTTPMethods.get
    var params:[String:String]?
    enum HTTPMethods: String { // http methods
        case get = "GET"
        case post = "POST"
        case put = "PUT"
        case patch = "PATCH"
        case delete = "DELETE"
    }
    
    func urlString(_ urlString: String?) -> APICaller {
        
        if let urlString = urlString {
        self.url = URL(string: urlString)
        }
        return self
    }
    
    func method(_ method:HTTPMethods) -> APICaller {
        self.method = method
        return self
    }
    
    func parameters(_ params:[String:String]) -> APICaller {
        self.params = params
        return self
    }
    
    func response(response:@escaping([String:AnyObject]) -> Void) {
        // create URLRequest with the http method, url, parameters etc and do the api call using URLSession method.. say use DataTask.
        let resultDictionary = ["result":["Result values1","Result values2","Result values3","Result values4"]]
        // let resultDictionary be the output of the API call made. Now, call the completion closure and pass the value .
        //DispatchQueue.main.async {
            response(resultDictionary as [String:AnyObject])
       // }
        
    }
}