Swift - Declare a global NSDate without value

Question

I want to create a global NSDate in my app, because I want to save the date of the first time ever the app has been opened in this variable. I wrote "var LaunchDate = NSDate()" before the declaration of the main class of the first view controller, and in the viewdidload, if it is the first time the app is opened, it saves the date into the global variable LaunchDate. But everytime I open the app, it saves the current date because of "var LaunchDate = NSDate()". I didn't find a solution, do you have any idea to declare a global date without that he gives the current date please?

Look at my answer... Write me if that did it @Oscar – Tom el Safadi Jan 30 '16 at 10:46 — Tom el Safadi, Jan 30 '16 at 10:46
Do you want to persist the date between launches? – Peba Jan 30 '16 at 10:48 — Peba, Jan 30 '16 at 10:48
@Anokrize I replied in a comment :) – Oscar Falmer Jan 30 '16 at 10:50 — Oscar Falmer, Jan 30 '16 at 10:50

vadian · Accepted Answer · 2016-01-30T11:00:22.270

You could use NSUserDefaults to store the value.

The code checks if a value exists.
If yes it reads the value, if no it writes the current date.

var launchDate : NSDate!

let defaults = NSUserDefaults.standardUserDefaults()
if let dateOfFirstLaunch = defaults.objectForKey("dateOfFirstLaunch") as? NSDate {
  launchDate = dateOfFirstLaunch
} else {
  let currentDate = NSDate()
  defaults.setObject(currentDate, forKey:"dateOfFirstLaunch")
  launchDate = currentDate
}

Tom el Safadi · Answer 2 · 2016-01-30T10:59:42.040

0

Try this:

override func viewDidLoad() {
    var LaunchDate: NSDate

    // when you want to set the value for it:
    LaunchDate = NSDate()
}

The Proble, is that NSDate() which you tried to do is a function, which gets back a value of the current date.

edited Jan 30 '16 at 10:59

answered Jan 30 '16 at 10:44

Tom el Safadi

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Thank you but you don't exactly answer the problem, I want LaunchDate to be a global variable (to use it in another ViewController) – Oscar Falmer Jan 30 '16 at 10:47
Then the approach would be to create a struct and you can access the variable from anywhere – Tom el Safadi Jan 30 '16 at 10:50
@Oscar look at this: https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/ClassesAndStructures.html. Structs have the advantage that you can use them all over your classes. Then you can simply access the variable and its values – Tom el Safadi Jan 30 '16 at 10:51
Great ! Do you have an example please ? – Oscar Falmer Jan 30 '16 at 10:51
Yes look above @Oscar – Tom el Safadi Jan 30 '16 at 10:52
Just make a new file as you would for a class and then write your variables into this structure – Tom el Safadi Jan 30 '16 at 10:52
I am going to try with this way :) – Oscar Falmer Jan 30 '16 at 10:53
Good! Remember to add the attribute static in a struct – Tom el Safadi Jan 30 '16 at 11:00

score 0 · Answer 3 · edited May 23 '17 at 11:52

0

Global variables are variables that are defined outside of any function, method, closure, or type context

struct globalDate 
{
   static var LaunchDate = NSDate()
}

In swift if you encapsulate the variable in struct, you can access that in any classes.

Document

Global Variable

edited May 23 '17 at 11:52

Community

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answered Jan 30 '16 at 10:58

user3182143

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score 0 · Answer 4 · answered Jan 30 '16 at 11:02

I would use the Singleton Pattern with NSUserDefaults.

The code should be something like this

import Foundation

class UserDefaults {
    static let sharedInstance = UserDefaults()

    var launchDate: NSDate? {
        get {
            return NSUserDefaults.standardUserDefaults().objectForKey("launch_date") as? NSDate
        }
        set {
            NSUserDefaults.standardUserDefaults().setObject(newValue, forKey: "launch_date")
        }
    }
}

Access it using this code

UserDefaults.sharedInstance.launchDate

Swift - Declare a global NSDate without value

4 Answers4