Passing data from completion block to view controller swift 3

Question

!I have been stuck for 2 days on this issue. Here is my scenario.

User clicks login button, if email address and password are stored in UserDefaults, the app silently login the user in, first presenting an UIAlertController while retrieving the user's data from the server. Once the data is returned to the app, a completion handler assigns a local property var User: [String: AnyObject] the results. I can print(self.User) at this point and the data is properly assigned. All good. The problem occur when I try to pass this data to the next controller that I am presenting via present. Here is my code:

LoginViewController.swift

-----

    dismiss(animated:true, completion: {
        let tenantViewController = storyboard.instantiateViewController(withIdentifier :"tenantDashboardViewController") as! TenantDashboardViewController
        tenantViewController.User = user
        print(tenantViewController.User) //Works
        self.present(tenantViewController, animated: true)
     })

Here is my destination viewcontroller

import Foundation
import SideMenuController

class TenantDashboardViewController: SideMenuController {


    var User: [String: AnyObject]?

    override func viewDidLoad() {
        super.viewDidLoad()

        performSegue(withIdentifier: "showTenantDashboardHomeViewController", sender: nil)
        performSegue(withIdentifier: "containTenantSideMenu", sender: nil)

        print(self.User!) //Always returns nil, crashes app

    }
}

Thanks in advance!

Try passing data in `func prepare(for segue: UIStoryboardSegue, sender: Any?)`. — triandicAnt, Nov 01 '16 at 04:10
Also side note: You should not be storing sensitive user data like passwords in `UserDefaults`. Use the Keychain. — Matthew Seaman, Nov 01 '16 at 04:12
@triple.s I'll add the prepare to the destination view controller? — David Davis Jr., Nov 01 '16 at 04:19
No.. in the source view controller.. in your case `LoginViewController`. Remember you are preparing to land in your destination `viewcontroller`. Therefore you need all your preparation beforehand :D (http://stackoverflow.com/a/31934786/2301570) — triandicAnt, Nov 01 '16 at 04:22
Thank you for the help, but I think I'll try what @brandonscript suggested — David Davis Jr., Nov 01 '16 at 04:30

score 1 · Accepted Answer · answered Nov 01 '16 at 04:22

1

If you're storing a user object app-side, you should store the User Object in NSUserDefaults. Make it NSCoding compliant so you can encode/decode the User class as you need to.

Then, as Matthew states, store your username/password combo in Keychain, because it is extremely sensitive and Keychain is designed to protect your users' credentials in a secure way.

answered Nov 01 '16 at 04:22

brandonscript

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I upvoted this because this is exactly what I need to do. Thank you! – David Davis Jr. Nov 01 '16 at 04:29

Passing data from completion block to view controller swift 3

1 Answers1