How can I Save Json Data and Show Offline in swift - ios

Question

I'm trying to save my json file and show it to offline. I'm trying this code but it is not working for me ..
let myData = NSKeyedArchiver.archivedData(withRootObject: self.data)
UserDefaults.standard.set(myData, forKey: "userJson")
UserDefaults.standard.synchronize()
Can any one suggest me better way to save data and show off line ?

Answer 1

You should not save JSON in the UserDefault, Instead save it in file in document directory
I have created generic class which allows to do it easily
//
// OfflineManager.swift
//
//
// Created by Prashant on 01/05/18.
// Copyright © 2018 Prashant. All rights reserved.
//
import UIKit
class OfflineManager: NSObject {
static let sharedManager = OfflineManager()
let LocalServiceCacheDownloadDir = "LocalData"
enum WSCacheKeys {
case CampignList
case CampignDetail(id:String)
case ScreenShotList
var value:String {
switch self {
case .CampignList:
return "CampignList"
case .CampignDetail(let id):
return id
case .ScreenShotList :
return "ScreenShotList"
}
}
}
func getBaseForCacheLocal(with fileName:String) -> String? {
let filePath = FileManager.default.getDocumentPath(forItemName: self.LocalServiceCacheDownloadDir)
if FileManager.default.directoryExists(atPath: filePath) {
return filePath.stringByAppendingPathComponent(fileName)
} else {
if FileManager.default.createDirectory(withFolderName: self.LocalServiceCacheDownloadDir) {
return filePath.stringByAppendingPathComponent(fileName)
}
}
return nil
}
//------------------------------------------------------------
#discardableResult
func cacheDataToLocal<T>(with Object:T,to key:WSCacheKeys) -> Bool {
let success = NSKeyedArchiver.archiveRootObject(Object, toFile: getBaseForCacheLocal(with: key.value)!)
if success {
print( "Local Data Cached\(String(describing: getBaseForCacheLocal(with: key.value)))")
} else {
print("Error")
}
return success
}
//------------------------------------------------------------
func loadCachedDataFromLocal<T>(with key:WSCacheKeys ) -> T? {
return NSKeyedUnarchiver.unarchiveObject(withFile: getBaseForCacheLocal(with: key.value)!) as? T
}
//------------------------------------------------------------
func removeAllCacheDirs () {
do {
try FileManager.default.removeItem(atPath: self.getBaseForCacheLocal(with: "")!)
} catch {
print("error in remove dir \(error.localizedDescription)")
}
}
//--------------------------------------------------------------------------------
}
Here is some helper methods of extension FileManager
public var getDocumentDirectoryPath: String {
let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
return documentDirectory
}
public func getDocumentPath(forItemName name: String)-> String {
return getDocumentDirectoryPath.stringByAppendingPathComponent(name)
}
public func directoryExists(atPath filePath: String)-> Bool {
var isDir = ObjCBool(true)
return FileManager.default.fileExists(atPath: filePath, isDirectory: &isDir )
}
public func createDirectory(withFolderName name: String)-> Bool {
let finalPath = getDocumentDirectoryPath.stringByAppendingPathComponent(name)
return createDirectory(atPath: finalPath)
}
Here Is String extension's method
public func stringByAppendingPathComponent(_ path: String) -> String {
let fileUrl = URL.init(fileURLWithPath: self)
let filePath = fileUrl.appendingPathComponent(path).path
return filePath
}
How to use it ?
To save
OfflineManager.sharedManager.cacheDataToLocal(with: object as! [String:Any], to: .CampignList)
To read data
DispatchQueue.global().async {
// GET OFFLINE DATA
if let object:[String:Any] = OfflineManager.sharedManager.loadCachedDataFromLocal(with: .CampignList) {
do {
let data = try JSONSerialization.data(withJSONObject: object, options: [])
let object = try CampaignListResponse.init(data: data)
self.arrCampignList = object.data ?? []
DispatchQueue.main.async {
self.tableVIew.reloadData()
}
} catch {
}
}
}
Note: You can define your own WSCacheKeys for type of your json like i am fetching some campaign list

Answer 2

You can use Realm or CoraData for saving data and showing it when you are offline.
Here is the official link for Realm.You can learn from here.
https://realm.io/docs/swift/latest