how to write data in the local json file iOS Swift?

Question

if let path = Bundle.main.path(forResource: "domaines", ofType: "json") {
    if JSONSerialization.isValidJSONObject(dict){
        do{
            let rawData = try JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted)
            try rawData.write(to: URL(fileURLWithPath: path))
        }catch{
        }
    }else{
    }
}else{
    print("file not present")
}

This is the code used by me but I'm not able to save the data to the local JSON file.

It's not possible. Files in the application bundle are read-only (for obvious reasons). — vadian, Feb 06 '20 at 11:57
You can write this in Document directory if you want, but not in Bundle. Bundle are read-only — Prashant Tukadiya, Feb 06 '20 at 12:06
can we create a local JSON file and then write data in it? @PrashantTukadiya . if yes then how? — Pathak Ayush, Feb 06 '20 at 12:06
@ap00724 Yes You can Create Local JSON file and write data into document directory have a look this wrapper classes in my github https://github.com/PrashantKT/Swift4-Locally-save-JSON- — Prashant Tukadiya, Feb 06 '20 at 12:07
@PrashantTukadiya please update the code it have some issues. https://prnt.sc/qyf3wl — Pathak Ayush, Feb 06 '20 at 12:36
@ap00724 Thanks for report, Will update this library when I will get time :) — Prashant Tukadiya, Feb 06 '20 at 12:44
There are plenty of examples online on how to save a file locally using swift in for instance the document directory. Search here on SO or google — Joakim Danielson, Feb 06 '20 at 13:36

score 0 · Answer 1 · answered Feb 06 '20 at 13:59

well, I created a class by which you can create a JSON file then add data to bypassing an array to it and you can update it by replacing data with the new data. check out my code and comment if you don’t understand anything.

it's easy to understand, it's easy to implement.

//  offlineJsonFileManager.swift
//  BuzCard
//
//  Created by ap00724 on 06/02/20.
//  Copyright © 2020 ap00724. All rights reserved.
//

import Foundation
import UIKit

class offlineJsonFileManager: NSObject {

    static let sharedManager = offlineJsonFileManager()

    func saveToJsonFile(fileName:String,dict:[[String:Any]]) {
        guard let documentDirectoryUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
        let fileUrl = documentDirectoryUrl.appendingPathComponent("\(fileName).json")

        let personArray = dict

        // Transform array into data and save it into file
        do {
            let data = try JSONSerialization.data(withJSONObject: personArray, options: [])
            try data.write(to: fileUrl, options: [])
        } catch {
            print(error)
        }
    }
    func retrieveFromJsonFile(fileName:String,completion:(Bool,[[String:Any]])->()) {
        // Get the url of Persons.json in document directory
        guard let documentsDirectoryUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else {
            completion(false,[["error":"file does not exist."]]);return }
        let fileUrl = documentsDirectoryUrl.appendingPathComponent("\(fileName).json")

        // Read data from .json file and transform data into an array
        do {
            let data = try Data(contentsOf: fileUrl, options: [])
            guard let personArray = try JSONSerialization.jsonObject(with: data, options: []) as? [[String:Any]] else { return }
            completion(true,personArray)
        } catch {
            print(error)
            completion(false,[["error":"\(error)"]])
        }
    }
}

Why a completion handler in the `load` method? Everything is synchronous. And rather than returning an extra `Bool` make the method `throw` and (re)throw the error — vadian, Feb 06 '20 at 14:10
completion was as per my requirements you can remove if you want. @vadian — Pathak Ayush, Feb 07 '20 at 12:36

score 0 · Answer 2 · answered Feb 06 '20 at 16:10

private func saveDomaines(json: [[String: Any]]) {
    if let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).last {
        let fileURL = documentsDirectory.appendingPathComponent("domaines.json")
        print("File exists")
        writeFile(fileURL: fileURL, json: json)
    } else {
        print("Shouldn't reach here")
    }
}

private func writeFile(fileURL: URL, json: [[String: Any]]) {
    do {
        if let jsonData = try JSONSerialization.data(withJSONObject: json, options: .init(rawValue: 0)) as? Data {
            try jsonData.write(to: fileURL)
        }
    } catch {
        print(error.localizedDescription)
    }
}

how to write data in the local json file iOS Swift?

2 Answers2