Instance Member Cannot Be Used on Type when pushing UIViewController

Question

I am programmatically setting up ViewControllers (no storyboard).

I want to pass data to the next VC, and while I know how to do that with a segue and a storyboard, I can't figure out how to do it purely programmatically.

I get the error "Instance Member Cannot Be Used on Type..."

// Create Next View Controller Variable

let nextViewController = CarbonCalculatorResultsViewController()

// Pass data to next view controller.  There is already a variable in that file: var userInformation: UserInformation?

CarbonCalculatorResultsViewController.userInformation = userInformation

// Push next View Controller
self.navigationController?.pushViewController(nextViewController, animated: true)

Do I need to instantiate the next VC before I can pass data? That's what this answer seems to talk about yet I don't have a Storyboard. Thanks!

score 2 · Accepted Answer · answered Feb 06 '19 at 18:40

Step 1: Setup your destination class

In CarbonCalculatorResultsViewController class, declare a var to receive data like so:

class CarbonCalculatorResultsViewController: UIViewController {
    var foo: String? {
        didSet {
            // What you'd like to do with the data received
            print(foo ?? "")
        }
    }

    ovevride func viewDidLoad() {
       //
    }
}

Step 2: Prepare data in your source class

let nextViewController = CarbonCalculatorResultsViewController()
// You have access of the variable in CarbonCalculatorResultsViewController
nextViewController.foo = <data_you_want_to_pass>

// Push next View Controller
self.navigationController?.pushViewController(nextViewController, animated: true)

Then, every time the CarbonCalculatorResultsViewController comes alive, the didSet{} of foo would be called.

Gustavo Vollbrecht · Answer 2 · 2019-02-06T15:59:46.027

You should pass the variable on the Object, not on the Class

Replace: CarbonCalculatorResultsViewController.userInformation = userInformation

With: nextViewController.userInformation = userInformation

Note:

CarbonCalculatorResultsViewController is the Class.

nextViewController is the Object.

Your full code should look like this:

// Create Next View Controller Variable

let nextViewController = CarbonCalculatorResultsViewController()

// Pass data to next view controller.  There is already a variable in that file: var userInformation: UserInformation?

nextViewController.userInformation = userInformation

// Push next View Controller
self.navigationController?.pushViewController(nextViewController, animated: true)

score 1 · Answer 3 · answered Feb 06 '19 at 15:54

The current sample code (above) is setting a value to a static variable (owned by the CarbonCalculatorResultsViewController.Type.

What I believe you want to implement is the following instead:

// Create Next View Controller Variable

let nextViewController = CarbonCalculatorResultsViewController()

// Pass data to next view controller.  There is already a variable in that file: var userInformation: UserInformation?

nextViewController.userInformation = userInformation

// Push next View Controller
self.navigationController?.pushViewController(nextViewController, animated: true)

This sample code is setting a value to the instance variable userInformation on the type nextViewController.

Instance Member Cannot Be Used on Type when pushing UIViewController

3 Answers3