Swift 4, load next ViewController

问题:

In my app I have two View Controllers embedded in Navigation Controller. And I want to have an option to get data from the SecondVC while only the FirstVC is opened. So it's like I don't want a user to see (or at least interact) with the SecondVC.

The point is

So user just taps on the button on the FirstVC (without opening SecondVC before) and I can get access to the data on the SecondVC. How can I get data from the next view controller (SecondVC) in a navigation controller without opening it? Or at least not letting user to interact with it.

For now my only ideas are:

1. To push segue when user taps a button, get it into memory, load data and then dismiss it. But that doesn't look good when view controllers change so fast.

2. To present next view controller modally offscreen, get data and dismiss it. So the user won't even see that another view controller opened.

Edit:

I need to get access not just to method or smth. I need to get to the @IBOutlet. To the subclass of UIView (working with CorePlot) to be exactly

回答1:

You should never call loadView() directly.

Instantiate your UIViewController and then call loadViewIfNeeded().

Calling this method loads the view controller’s view from its storyboard file, or creates the view as needed based on the established rules.

EDIT:

let storyboard = UIStoryboard(name: "Main", bundle: nil)

// make sure that the value is an optional so that you can unset it later. This one is optional because we use optional casting (with as?)
var vc = storyboard.instantiateViewController(withIdentifier: "secondVC") as? SecondViewController
vc?.loadViewIfNeeded()

// use the vc

// later unset vc variable
vc = nil

回答2:

for this, you must call your 2ed View controller with 'modalPresent' and background of 2edVC must clear. Then get your data from 2ed VC. with no change. for more information about modalPresent there is the link.

回答3:

Solution:

You can create a function for it or just insert in viewDidLoad() etc.

Don't forget to change StoryboardID for the chosen view controller (it can be done in your storyboard file in Identity inspector).

    // You need to get to your Storyboard and instantiate the needed View Controller
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    var graphVC = storyboard.instantiateViewController(withIdentifier: "graphVCID") as? graphVC

    // Then call loadViewIfNeeded (don't call loadView()) to load @IBOutlet's etc
    graphVC?.loadViewIfNeeded()

    // My outlets are loaded with data when these functions are called
    graphVC?.viewDidLoad()
    graphVC?.viewWillAppear(false)

    // Unset the reference to VC
    graphVC = nil