swift4: can't pass value to previous view controller from current popover - ios

Question

I'm using swift4, i present view controller modally as popover and want to pass data back to previous view controller when dismissing current popover, this is the first View controller :
import UIKit
class SearchResultViewController: UIViewController, UIPopoverPresentationControllerDelegate, PopoupDelegate {
#IBOutlet var errorLable: UILabel!
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "pop") {
let dest = segue.destination
if let pop = dest.popoverPresentationController {
dest.preferredContentSize = CGSize(width: self.view.frame.size.height - 20, height: 500)
pop.delegate = self
}
}
}
func adaptivePresentationStyle(for controller: UIPresentationController) -> UIModalPresentationStyle {
return .none
}
func popupValueSelected(value: String) {
print("value: ", value)
self.errorLable.text = value
}
}
and this the popover code:
import UIKit
class SearchPopoverViewController: UIViewController {
#IBOutlet var cityLable: UILabel!
var delegate: PopoupDelegate?
#IBAction func closeButtonAction(_ sender: Any) {
self.delegate?.popupValueSelected(value: "hiiiiii from the other side")
self.dismiss(animated: false, completion: nil)
}
}
and this is the PopoupDelegate
import Foundation
protocol PopoupDelegate {
func popupValueSelected(value: String)
}
when i click in the popover close button, the popover should dismiss and the errorLable in SearchResultViewController should change it's text to new passed text, but none happens, only the popover dismiss,
what should i do?

Answer 1

You delegate function is wrong, function inside function in SearchResultViewController:
func popupValueSelected(value: String) {
func popupValueSelected(value: String) {
print("value: ", value)
self.errorLable.text = value
}
}
It should be:
func popupValueSelected(value: String) {
print("value: ", value)
self.errorLable.text = value
}
After editing the question :
You never assigned any instance to the delegate variable. Try to change delegate variable name to popoUpDelegate.
pop.delegate is for UIPopoverPresentationControllerDelegate not your delegate. This function should be like this :
if (segue.identifier == "pop") {
if let dest = segue.destination.popoverPresentationController as? SearchPopoverViewController {
dest.preferredContentSize = CGSize(width: self.view.frame.size.height - 20, height: 500)
dest.popoUpDelegate = self
}
}
}
And your SearchPopoverViewController look like this :
class SearchPopoverViewController: UIViewController {
#IBOutlet var cityLable: UILabel!
var popoUpDelegate: PopoupDelegate?
#IBAction func closeButtonAction(_ sender: Any) {
self.popoUpDelegate?.popupValueSelected(value: "hiiiiii from the other side")
self.dismiss(animated: false, completion: nil)
}
}

Answer 2

you have to define delegate to SearchResultViewController.
var PopoupDelegate : PopoupDelegate?
and before pop viewcontroller assign delegate to popoupDelegate
PopoupDelegate.delegate = self
and you have right function inside function. first make it correct.
Try this. Hope this will work. and let me know in case of any concern

Answer 3

When you are presenting SearchPopoverViewController from SearchResultViewController you need to set delegate.
Using segue
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "segueToPopOver") {
let dest = segue.destination
if let vc = dest.popoverPresentationController as? SearchPopoverViewController {
//set other properties
vc.delegate = self
}
}
}
Using UINavigationController
let vc = SearchPopoverViewController() // initialise view controller
vc.delegate = self
present(vc, animated: true, completion: nil)
Respond to delegate
#IBAction func closeButtonAction(_ sender: Any) {
self.delegate?.popupValueSelected(value: "hiiiiii from the other side")
self.dismiss(animated: false, completion: nil)
}
In SearchResultViewController implement delegate method
func popupValueSelected(value: String) {
print("value: ", value)
self.errorLable.text = value
}

Answer 4

I think you have a fundamental misunderstanding as to how segues and protocols work for view controllers. Frankly, I would recommended reviewing the topic in Apple's App Development with Swift. This is written clearly with exercises to help you understand the basics of passing information between view controllers. I have been where you are, and while the suggestions and comments have been correct, you don't seem to have the foundation to understand what they are saying. Good luck!

Answer 5

I used popover dismiss delegate instead of protocol:
this code solved my problem:
in the SearchResultViewController:
func popoverPresentationControllerDidDismissPopover(_ popoverPresentationController: UIPopoverPresentationController) {
if let searchPopoverViewController =
popoverPresentationController.presentedViewController as? SearchPopoverViewController{
self.passed_city_id = searchPopoverViewController.selected_city_id
}
}
in the SearchPopoverViewController
#IBAction func searchButtonAction(_ sender: Any) {
self.selected_city_id = 10
popoverPresentationController?.delegate?.popoverPresentationControllerDidDismissPopover?(popoverPresentationController!)
self.dismiss(animated: true, completion: nil)
}

Answer 6

you can use "Unwind segue". pls refer
https://medium.com/#mimicatcodes/create-unwind-segues-in-swift-3-8793f7d23c6f