Network Helper for iOS with custom caching and bootstrapping suppory

NetworkHelper.swift

//
//  NetworkHelper.swift
//  acrypto
//
//  Created by HaKr on 21/10/17.
//  Copyright © 2017 DWorkS. All rights reserved.
//
import Foundation
import Alamofire

public protocol NetworkCompletionDelegate {
    
    func onResponse(_ response: Any)
    
    func onErrorResponse(_ error: Error)
}

class NetworkHelper: NSObject {

    static var sessionManager: SessionManager!
    static var sessionConfiguration: URLSessionConfiguration!
    
    static var sessionManagerMaster: SessionManager!
    static var sessionConfigurationMaster: URLSessionConfiguration!
    
    static func getSessionManger() -> SessionManager {
        if(nil == sessionManager) {
            let capacity = 50 * 1024 * 1024 // MBs
            let urlCache = SmartUrlCache(memoryCapacity: capacity, diskCapacity: capacity, diskPath: nil)
            sessionConfiguration = URLSessionConfiguration.default
            sessionConfiguration.requestCachePolicy = .returnCacheDataElseLoad
            sessionConfiguration.urlCache = urlCache
            sessionConfiguration.timeoutIntervalForRequest = 10
            sessionManager = Alamofire.SessionManager(configuration: sessionConfiguration)
        }
        return sessionManager
    }
    
    static func getSessionMangerMaster() -> SessionManager {
        if(nil == sessionManagerMaster) {
            let capacity = 50 * 1024 * 1024 // MBs
            let urlCache = SmartUrlMasterCache(memoryCapacity: capacity, diskCapacity: capacity, diskPath: nil)
            sessionConfigurationMaster = URLSessionConfiguration.default
            sessionConfigurationMaster.requestCachePolicy = .returnCacheDataElseLoad
            sessionConfigurationMaster.urlCache = urlCache
            sessionManagerMaster = Alamofire.SessionManager(configuration: sessionConfigurationMaster)
        }
        return sessionManagerMaster
    }
    
    static func removeCachedUrl(url: String, parameters: Parameters? = nil) {
        let headers: HTTPHeaders? = nil
        var originalRequest: URLRequest

        do {
            originalRequest = try URLRequest(url: url, method: .get, headers: headers)
            let encodedURLRequest = try URLEncoding.default.encode(originalRequest, with: parameters)
            sessionConfiguration.urlCache?.removeCachedResponse(for: encodedURLRequest)
            addCache(url: url, data: Data(), parameters: parameters)
        } catch  {
            Log.info(error)
        }
    }
    
    static func removeMasterCachedUrl(url: String, parameters: Parameters? = nil) {
        let headers: HTTPHeaders? = nil
        var originalRequest: URLRequest
        
        do {
            originalRequest = try URLRequest(url: url, method: .get, headers: headers)
            let encodedURLRequest = try URLEncoding.default.encode(originalRequest, with: parameters)
            sessionConfiguration.urlCache?.removeCachedResponse(for: encodedURLRequest)
            addMasterCache(url: url, data: Data(), parameters: parameters)
        } catch  {
            Log.info(error)
        }
    }
    
    static func removeAllCached() {
        sessionConfigurationMaster.urlCache?.removeAllCachedResponses()
    }
    
    static func addCache(url: String, data: Data, parameters: Parameters? = nil) {
        let headers: HTTPHeaders? = nil
        
        do {
            let originalRequest = try URLRequest(url: url, method: .get, headers: headers)
            let encodedURLRequest = try URLEncoding.default.encode(originalRequest, with: parameters)
            let newResponse = HTTPURLResponse(url: URL(string: url)!, statusCode: 200, httpVersion: "HTTP/1.1", headerFields: ["Cache-Control":"private, max-age=0, s-maxage=0"])
            let cachedResponse = CachedURLResponse(response: newResponse!, data: data)
            sessionConfiguration.urlCache?.storeCachedResponse(cachedResponse, for: encodedURLRequest)
        } catch  {
            Log.info(error)
        }
    }
    
    static func addMasterCache(url: String, data: Data, parameters: Parameters? = nil) {
        let headers: HTTPHeaders? = nil
        
        do {
            let originalRequest = try URLRequest(url: url, method: .get, headers: headers)
            let encodedURLRequest = try URLEncoding.default.encode(originalRequest, with: parameters)
            let newResponse = HTTPURLResponse(url: URL(string: url)!, statusCode: 200, httpVersion: "HTTP/1.1", headerFields: ["Cache-Control":"private, max-age=0, s-maxage=0"])
            let cachedResponse = CachedURLResponse(response: newResponse!, data: data)
            sessionConfigurationMaster.urlCache?.storeCachedResponse(cachedResponse, for: encodedURLRequest)
        } catch  {
            Log.info(error)
        }
    }
    
    static func requestJSON(_ url: String, _ parameters: Parameters, _ completionDelegate: NetworkCompletionDelegate){
        
        getSessionManger().request(url, method: .get, parameters: parameters)
            .validate()
            .responseJSON { response in
                switch response.result {
                case .success:
                    Log.info("Request: \(String(describing: response.request))")
                    completionDelegate.onResponse(response)
                    break
                case .failure(let error):
                    Log.info("Error: \(error)")
                    completionDelegate.onErrorResponse(error)
                }
        }
    }
    
    static func requestJSON(_ url: String, _ parameters: Parameters, _ completionHandler: @escaping (DataResponse<Any>) -> Void) {
        getSessionManger().request(url, method: .get, parameters: parameters).validate().responseJSON(completionHandler: completionHandler)
    }
    
    
    static func requestString(_ url: String, _ parameters: Parameters, _ completionDelegate: NetworkCompletionDelegate){
        getSessionManger().request(url, method: .get, parameters: parameters)
            .validate()
            .responseString { response in
                switch response.result {
                case .success:
                    Log.info("Request: \(String(describing: response.request))")
                    completionDelegate.onResponse(response)
                    break
                case .failure(let error):
                    Log.info("Error: \(error)")
                    completionDelegate.onErrorResponse(error)
                }
        }
    }
    
    static func requestString(_ url: String, _ parameters: Parameters, _ completionHandler: @escaping (DataResponse<String>) -> Void) {
        getSessionManger().request(url, method: .get, parameters: parameters).validate().responseString(completionHandler: completionHandler)
    }
    
    static func requestJSONMaster(_ url: String, _ parameters: Parameters, _ completionDelegate: NetworkCompletionDelegate){
        getSessionMangerMaster().request(url, method: .get, parameters: parameters, headers: getHeaders())
            .validate()
            .responseJSON { response in
                switch response.result {
                case .success:
                    Log.info("Request: \(String(describing: response.request))")
                    completionDelegate.onResponse(response)
                    break
                case .failure(let error):
                    Log.info("Error: \(error)")
                    completionDelegate.onErrorResponse(error)
                }
        }
    }
    
    static func requestJSONMaster(_ url: String, _ parameters: Parameters, _ completionHandler: @escaping (DataResponse<Any>) -> Void) {
        getSessionMangerMaster().request(url, method: .get, parameters: parameters, headers: getHeaders()).validate().responseJSON(completionHandler: completionHandler)
    }
    
    
    static func requestStringMaster(_ url: String, _ parameters: Parameters, _ completionDelegate: NetworkCompletionDelegate){
        getSessionMangerMaster().request(url, method: .get, parameters: parameters, headers: getHeaders())
            .validate()
            .responseString { response in
                switch response.result {
                case .success:
                    Log.info("Request: \(String(describing: response.request))")
                    completionDelegate.onResponse(response)
                    break
                case .failure(let error):
                    Log.info("Error: \(error)")
                    completionDelegate.onErrorResponse(error)
                }
        }
    }
    
    static func requestStringMaster(_ url: String, _ parameters: Parameters, _ completionHandler: @escaping (DataResponse<String>) -> Void) {
        getSessionMangerMaster().request(url, method: .get, parameters: parameters, headers: getHeaders()).validate().responseString(completionHandler: completionHandler)
    }
    
    static func getHeaders() -> HTTPHeaders{
        var headers: HTTPHeaders = [:]
        headers.updateValue(Constants.AUTH, forKey: Constants.AUTH_HEADER)
        headers.updateValue(AppHelper.versionName ?? "", forKey: Constants.CLIENT_HEADER)
        return headers
    }
}

class SmartUrlCache: URLCache {
    let CACHE_EXPIRY = "cache_expiry";
    let cacheExpireInterval: TimeInterval = 60*60;
    
    override func cachedResponse(for request: URLRequest) -> CachedURLResponse? {
        var response: CachedURLResponse? = nil
        
        if let cachedResponse = super.cachedResponse(for: request) {
            if let userInfo = cachedResponse.userInfo {
                if let cacheDate = userInfo[CACHE_EXPIRY] as! NSDate? {
                    
                    // check if the cache data are expired
                    let count = cachedResponse.data.count
                    if (cacheDate.timeIntervalSinceNow < -cacheExpireInterval) || count == 0 {
                        self.removeCachedResponse(for: request)
                    } else {
                        response = cachedResponse
                    }
                }
            }
        }
        
        return response;
    }
    
    override func removeCachedResponse(for request: URLRequest) {
        super.removeCachedResponse(for: request)
    }
    
    override func storeCachedResponse(_ cachedResponse: CachedURLResponse, for request: URLRequest) {
        var userInfo = NSMutableDictionary()
        if let cachedUserInfo = cachedResponse.userInfo {
            userInfo = NSMutableDictionary(dictionary: cachedUserInfo)
        }
        
        if let cacheDate = userInfo[CACHE_EXPIRY] as! NSDate? {
            // check if the cache data are expired
            if (cacheDate.timeIntervalSinceNow < -cacheExpireInterval) {
                userInfo[CACHE_EXPIRY] = NSDate()
            }
        } else {
            userInfo[CACHE_EXPIRY] = NSDate()
        }

        let newCachedResponse = CachedURLResponse(response: cachedResponse.response, data: cachedResponse.data, userInfo: userInfo as [NSObject : AnyObject], storagePolicy: cachedResponse.storagePolicy)
        super.storeCachedResponse(newCachedResponse, for: request)
    }
}

class SmartUrlMasterCache: URLCache {

    override func cachedResponse(for request: URLRequest) -> CachedURLResponse? {
        var response: CachedURLResponse? = nil
        
        if let cachedResponse = super.cachedResponse(for: request) {
            let count = cachedResponse.data.count
            if count == 0 {
                self.removeCachedResponse(for: request)
            } else {
                response = cachedResponse
            }
        }
        
        return response;
    }
    
    override func removeCachedResponse(for request: URLRequest) {
        super.removeCachedResponse(for: request)
    }
}