JSONHandling.playground

//Just download and open this file in Xcode to play with the code!

import UIKit

var str = "Hello, playground"
//Constants.swift

struct Constants {
    static let userAppGroup = "B672DS45"
    static let pathToJSON = "path/to/file"
    
    struct Tables {
        static let tools = "tools__c" //e.g. these fieldnames are how Salesforce custom fields are structured
        static let accessories = "accessories__c"
        
        struct ToolsKeys {
            static let hammer = "hammer__c"
            static let wrench = "wrench__c"
            static let screwdriver = "screwdriver__c"
        }
    }
}

//sample.json
let jsonString: String =
"""
{
    "tools__c": {
        "hammer__c": "Stanley 5oz. Pro",
        "screwdriver__c": "Craftsman 9-31794 Slotted Phillips"
    },
    "accessories__c": {
        "nails__c": "nail brand"
    }
}
"""


//JSONHandler.swift

typealias Tables = Constants.Tables
typealias Keys = Tables.ToolsKeys

class JSONHandler {
    var json: Any?
    var data: Data
    var hammer = ""
    
    public init(pathAsString: String) { //pass in the filepath of the JSON
        var tempData: Data = Data()
        do {
            //tempData = try Data(contentsOf: URL(fileURLWithPath: pathAsString))
            tempData = jsonString.data(using: .utf8)! //doing a bad thing (!) for demonstration purposes
        }
        catch {
            print(error.localizedDescription)
        }
        self.data = tempData
        self.json = try? JSONSerialization.jsonObject(with: self.data)
    }

    public func getTools() {
        if let toolbox = json as? [String: Any] {
            if let tools = toolbox[Tables.tools] as? [String: Any] {
                if let hammer = tools[Keys.hammer], let screwdriver = tools[Keys.screwdriver] {
                    print("I have a hammer AND a wrench in my toolbox!")
                }
                //if we want to actually use the value, we need to tell the compiler what type we are expecting:
                if let hammer = tools[Keys.hammer] as? String {
                    self.hammer = hammer
                }
            }
        }
    }
}

//Main.swift
let jsonHandler = JSONHandler(pathAsString: Constants.pathToJSON)
jsonHandler.getTools()
print("The hammer I have is a", jsonHandler.hammer)