URLSession class for generic api calls in swift

APIClient.swift

//
//  PEAPIUtilityExt.swift
//  ProcializeEvents
//
//  Created by Chaitanya Soni on 21/06/20.
//  Copyright © 2020 Chaitanya Soni. All rights reserved.
//

import Foundation

public typealias JSON = [String: Any]
public typealias HTTPHeaders = [String: String]

public enum RequestMethod: String {
    case get = "GET"
    case post = "POST"
    case put = "PUT"
    case delete = "DELETE"
}

public class APIClient {
    static let shared = APIClient()
    
    public func sendRequest<T: Decodable>(for: T.Type = T.self,
                                          url: String,
                                          method: RequestMethod,
                                          headers: HTTPHeaders? = nil,
                                          body: JSON? = nil,
                                          completion: @escaping (Result<T>) -> Void) {
        
        return sendRequest(url: url, method: method, headers: headers, body:body, completion: completion) { decoder, data in try decoder.decode(T.self, from: data) }
    }
    
    public func sendRequest<T: Decodable>(for: [T].Type = [T].self,
                                          url: String,
                                          method: RequestMethod,
                                          headers: HTTPHeaders? = nil,
                                          body: JSON? = nil,
                                          completion: @escaping (Result<[T]>) -> Void) {
        
        return sendRequest(url: url, method: method, headers: headers, body:body, completion: completion) { decoder, data in try decoder.decode([T].self, from: data) }
    }
    
    private func sendRequest(_ url: String,
                             method: RequestMethod,
                             headers: HTTPHeaders? = nil,
                             body: JSON? = nil,
                             completionHandler: @escaping (Data?, URLResponse?, Error?) -> Void) {
        let url = URL(string: url)!
        var urlRequest = URLRequest(url: url)
        urlRequest.httpMethod = method.rawValue

        if let headers = headers {
            urlRequest.allHTTPHeaderFields = headers
            urlRequest.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
        }

        if let body = body {
            urlRequest.httpBody = try? JSONSerialization.data(withJSONObject: body)
        }

        let session = URLSession(configuration: .default)
        let task = session.dataTask(with: urlRequest) { data, response, error in
            completionHandler(data, response, error)
        }
        
        task.resume()
    }
    
    private func sendRequest<T>(url: String,
                                method: RequestMethod,
                                headers: HTTPHeaders? = nil,
                                body: JSON? = nil,
                                completion: @escaping (Result<T>) -> Void,
                                decodingWith decode: @escaping (JSONDecoder, Data) throws -> T) {
        return sendRequest(url, method: method, headers: headers, body:body) { data, response, error in
            guard let data = data else {
                return completion(.failure((error ?? NSError(domain: "SomeDomain", code: -1, userInfo: nil)) as NSError))
            }
            do {
                let decoder = JSONDecoder()
                // asking the custom decoding block to do the work
                try completion(.success(decode(decoder, data)))
            } catch let decodingError {
                completion(.failure(decodingError as NSError))
            }
        }
    }
    
    
}

`

private func sendRequest(_ url: String,
method: RequestMethod,
headers: HTTPHeaders? = nil,
body: JSON? = nil,
completionHandler: @escaping (Data?, URLResponse?, Error?) -> Void) {

	guard let formatedURL = url.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed),
		  let url = URL(string: formatedURL) else {
		return
	}

	var urlRequest = URLRequest(url: url)
	urlRequest.httpMethod = method.rawValue
	
	if let headers = headers {
		urlRequest.allHTTPHeaderFields = headers
		urlRequest.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
	}
	
	if let body = body {
		urlRequest.httpBody = try? JSONSerialization.data(withJSONObject: body)
	}
	
	let session = URLSession(configuration: .default)
	let task = session.dataTask(with: urlRequest) { data, response, error in
		completionHandler(data, response, error)
	}
	
	task.resume()
}

`

For allowing whitespaces in get request