Pass text to TextView via Segue - ios

Question

I'm trying to pass text to TextView from other ViewController:
if (segue.identifier == "HomeToDetails") {
let nav = segue.destination as! UINavigationController
let nextVC = nav.topViewController as! DetailsViewController
nextVC.infoTextView.text = "TESTING"
}
But it crashes:
fatal error: unexpectedly found nil while unwrapping an Optional value

Answer 1

setting text on UITextField of DestinationViewController is not possible in the prepareForSegue:sender, because all view components of the recently allocated controller are not initialized before the view is loaded (at this time, they are all nil), they only will be when the DestinationViewController view is loaded.
You need to use optional variable infoString in DetailsViewController which you can set in prepareForSegue method
if (segue.identifier == "HomeToDetails") {
let nav = segue.destination as! UINavigationController
let nextVC = nav.topViewController as! DetailsViewController
nextVC.infoString = "TESTING"
}
in DetailsViewController.swift
class DetailViewController: UIViewController {
var infoString: String?
override func viewDidLoad() {
super.viewDidLoad()
if let info = infoString {
self.infoTextView.text = info
}
}
}

Answer 2

if value is nil and you unwrap it, then the app will crash, you should use optional binding to avoid crash.
if (segue.identifier == "HomeToDetails") {
if let nav = segue.destination as? UINavigationController { //should use optional binding to avoid crash
if let nextVC = nav.topViewController as? DetailsViewController {
nextVC.infoTextView.text = "TESTING"
}
}
}

Answer 3

Check this:
if (segue.identifier == "HomeToDetails") {
// get a reference to the second view controller
let secondViewController = segue.destination as! DetailsViewController
// set a variable in the second view controller with the String to pass
secondViewController.infoTextView.text = "TESTING"
}

Answer 4

Try this code:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let nav = segue.destination as? UINavigationController {
if let nextVC = nav.topViewController as? DetailsViewController {
nextVC.infoTextView.text = "Data you want to pass"
}
}
}

Answer 5

this is because when you are assigning value to text view, the text view not initialized that time as viewDidLoad of next class is not called yet. So pass only string, then in viewDidLoad of next class, set the text.

Answer 6

You cannot pass a text directly to TextView in another view before it's created.
First ViewController:
if (segue.identifier == "HomeToDetails") {
let secondViewController = segue.destination as! DetailsViewController
secondViewController.myText = "TESTING"
}
DetailsViewController:
var myText = ""
override func viewDidLoad() {
super.viewDidLoad()
infoTextView.text = myText
}

Answer 7

All view components of the DetailsViewController are not initialized before the view is loaded. You can load that view before assigning values to the components of that view
Consider vC is the view controller which contains the view that you want to load. Then
if let _ = vC.view {
//Assign value here
}
Once the view is loaded, we can set the value to the components in that view. In SWIFT 3
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "HomeToDetails" {
let nav = segue.destination as! UINavigationController
let nextVC = nav.topViewController as! DetailsViewController
if let _ = nextVC.view {
nextVC.infoTextView.text = "TESTING"
}
}
}