How to access data in Class globally in any ViewController in the project

Question

I am a newbie in Swift.

Objective: Access the data globally

How to use Swift to implement a global Temporary storage using below class to store data

<

Answer 1

You can follow the step. How to set shared variable in Swift 3

1. Create a model file "TimetableModel.swift"

   import Foundation
   class TimetableModel {
       static let sharedInstance = TimetableModel()
       let categories:[Day]        
       var user_id = Int()
       // define any variable here
   }
   

2. After that create any controller

   import UIKit
   class TimetableVC: UIViewController {
       override func viewDidLoad() { // now you can access shared variable  
           TimetableModel.sharedInstance.categories[section].name    TimetableModel.sharedInstance.user_id
       }
   }
   

Answer 2

If your objective is to access the data globally for temporary storage, just create a struct for your transaction:

struct Transaction {
    let date: Date
    let quantity: Int
    let price: Double
    let code: String
}

Then just need to create a singleton and a property to store your transactions:

class Shared {
    private init() { }
    static var instance = Shared()
    var transactions: [Transaction] = []
}

---

usage:

Shared.instance.transactions.append(Transaction(date: Date(), quantity: 2, price: 0.99, code: "item01"))
Shared.instance.transactions.append(Transaction(date: Date(), quantity: 3, price: 2.99, code: "item02"))

Shared.instance.transactions  // [{date "Jan 10, 2017, 2:00 AM", quantity 2, price 0.99, code "item01"},
                              //  {date "Jan 10, 2017, 2:00 AM", quantity 3, price 2.99, code "item02"}]

looping through your transactions and editing it:

for (index, transaction) in Shared.instance.transactions.enumerated() {
    print(transaction)
    if transaction.code == "item02" {
        Shared.instance.transactions[index] = Transaction(date: transaction.date, quantity: transaction.quantity, price: transaction.price, code: "NEW CODE")
    }
}

Shared.instance.transactions   // [{date "Jan 10, 2017, 2:42 AM", quantity 2, price 0.99, code "item01"}, {date "Jan 10, 2017, 2:42 AM", quantity 3, price 2.99, code "NEW CODE"}]

---

If you want to have just a single transaction just add an optional variable to your Shared struct instead of the transactions array:

class Shared {
    private init() { }
    static var instance = Shared()
    var transaction: Transaction?
}

---

and usage:

Shared.instance.transaction = Transaction(date: Date(), quantity: 5, price: 5.0, code: "P200")

print(Shared.instance.transaction?.code ?? "")   // "P200\n"

if let transaction = Shared.instance.transaction {
    Shared.instance.transaction = Transaction(date: transaction.date, quantity: transaction.quantity, price: transaction.price, code: "P300")
    print(Shared.instance.transaction!)   // "Transaction(date: 2017-01-10 05:13:58 +0000, quantity: 5, price: 5.0, code: "P300")\n"

}