Pass data backward from detailViewController to masterViewController - ios

I am trying to pass data back from the second viewController.
I can do that without NavigationController. But now I need to use NavigationController. Then my code does work as before. The data wont pass.
Here is the simple code:
In first viewController
class ViewController: UIViewController, backfromSecond {
#IBOutlet weak var text: UILabel!
var string : String?
override func viewDidLoad() {
super.viewDidLoad()
self.string = "Start here"
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
self.text.text = self.string
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destinationViewController = segue.destination as? secondViewController{
destinationViewController.delegate = self
}
}
func back(text: String) {
self.string = text
print(text)
}
}
And Second viewController:
protocol backfromSecond {
func back(text: String)
}
class secondViewController: UIViewController {
var string : String = "nothing here"
var delegate : backfromSecond?
override func viewDidLoad() {
super.viewDidLoad()
delegate?.back(text: string)
// Do any additional setup after loading the view.
}
}
What is wrong here?

Suppose A & B are two controllers and you first navigated from A to B with some data. And now you want to POP from B to A with some data.
Unwind Segues is the best and recommended way to do this.
Here are the steps.
Open A.m
define following method
#IBAction func unwindSegueFromBtoA(segue: UIStoryNoardSegue) {
}
open storyboard
Select B ViewController and click on ViewController outlet. press control key and drag to 'Exit' outlet and leave mouse here. In below image, selected icon is ViewController outlet and the last one with Exit sign is Exit Outlet.
You will see 'unwindSegueFromBtoA' method in a popup . Select this method .
Now you will see a segue in your view controler hierarchy in left side. You will see your created segue near StoryBoard Entry Piont in following Image.
Select this and set an identifier to it. (suggest to set the same name as method - unwindSegueFromBtoA)
Open B.m . Now, wherever you want to pop to A. use
self.performSegueWithIdentifier("unwindSegueFromBtoA", sender: dataToSend)
Now when you will pop to 'A', 'unwindSegueFromBtoA' method will be called. In unwindSegueFromBtoA of 'A' you can access any object of 'B'.
That's it..!

I think your problem is in the prepare for segue method. If the view controller is on a navigation stack i think your code should be something like
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destinationViewController = segue.destination as? UINavigationController).topViewController as! secondViewController{
destinationViewController.delegate = self
}
}

You can use unwind segues to pass data back.
Here's a tutorial
https://spin.atomicobject.com/2014/10/25/ios-unwind-segues/

This works me well.
1st VC
class ViewController: UIViewController, backfromSecond {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func Passingfrom1stVCTo2ndVC(_ sender: AnyObject) {
if let vc = self.storyboard?.instantiateViewController(withIdentifier: "ViewController3") as? ViewController3{
vc.dataFrom1StVC = "message send from 1st VC"
vc.delegate = self
self.navigationController?.pushViewController(vc, animated: true)
}
}
func back(text: String) {
print("data\(text)")
}
}
2nd VC.
protocol backfromSecond: class {
func back(text: String)
}
class ViewController3: UIViewController {
var dataFrom1StVC : String? = nil
week var delegate : backfromSecond?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func DataSendFrom2ndVCTo1stVC(_ sender: AnyObject) {
self.delegate?.back(text: "Message Send From 2nd vc to 1st VC")
self.navigationController?.popViewController(animated: true)
}
}
I hope it will work you. If any problem then ask me i will help you.

Related

Delegate between TableViewController and ViewController

I'm in my first week of developing in iOS and have become stuck on an issue with passing data between view controllers. My set up consists of a view with VC having a button in it and also a container view (no associated view controller). The container view has an embedded Segue to a TableView with TableViewController. The table has 6 rows and each row has a stepper that can change the value of a text view on the associated row. What I would like to do is collect the values of all the textviews when I press the button on the main view.
I am trying to use delegate to do this but when I press the button the returned value is always nil. I believe the problem is to do with the fact the VC is not being passed to the table view controller via the prepareForSegue function but I'm not sure why? Could be to do with the load order of the controllers?
import UIKit
class PredictionViewController: UIViewController, PredictionDelegate {
var predictionData: String!
#IBOutlet weak var messageTextBox: UITextView!
#IBOutlet weak var predictionSubmitButton: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
self.messageTextBox.isEditable = false
}
override func viewDidAppear(_ animated: Bool) {
}
func prepareForSegue(segue: UIStoryboardSegue!, sender: AnyObject!) {
if (segue.identifier == "predictionSegue") {
// pass data to next view
let vc = segue.destination as! PredictionsTableViewController
vc.predictionHomeDelegate = self
}
}
func receiveData(with data: String) {
predictionData = data
print(predictionData)
}
#IBAction func predictionSubmitButtonAction(_ sender: UIButton) {
print(predictionData)
}
}
TableViewController: (stripped to minimum)
import UIKit
protocol PredictionDelegate: class {
func receiveData(with data: String)
}
class PredictionsTableViewController: UITableViewController, PredictionDelegate {
weak var predictionHomeDelegate: PredictionDelegate?
#IBOutlet weak var homeTeamScore1: UITextView!
#IBOutlet weak var homeTeamStepper1: UIStepper!
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewDidAppear(_ animated: Bool) {
}
func getPredictionList() {
//does some stuff
self.passDataBackwards()
}
func receiveData(with data: String) {}
func passDataBackwards() {
let data = "{\"score\":\"1\"}"
predictionHomeDelegate?.receiveData(with: data)
}
#IBAction func homeTeamStepper1Action(_ sender: UIStepper) {
let score = Int(sender.value).description
homeTeamScore1.text = score
self.passDataBackwards()
}
}
Any help gratefully received!
Edit:
After comments...
You have the wrong idea about Protocols and Delegates. They are not needed here.
Instead, in your "home" VC, get a reference to the embedded VC. Then, add a function in your embedded VC that you can call to get its data.
// "home" view controller
class PredictionViewController: UIViewController {
// this will be a reference to the embedded view controller
var embeddedVC: PredictionsTableViewController?
#IBAction func getDataButtonTapped(_ sender: Any) {
if let tableData = embeddedVC?.getMyData() {
print("Result: \(tableData)")
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "predictionSegue") {
if let vc = segue.destination as? PredictionsTableViewController {
// get a reference to the embedded VC
self.embeddedVC = vc
}
}
}
}
// embedded view controller
class PredictionsTableViewController: UIViewController {
var numTaps = 0
func getMyData() -> String {
return "\(numTaps)"
}
#IBAction func didTap(_ sender: Any) {
numTaps += 1
}
}
You're close, but a couple mistakes...
Here is a very, very simple example. View controller with container, which has a view controller with a button.
Code:
import UIKit
// your protocol
protocol PredictionDelegate: class {
func receiveData(with data: String)
}
// embedded view controller
// NOTE: this should NOT include PredictionDelegate
class PredictionsTableViewController: UIViewController {
weak var predictionHomeDelegate: PredictionDelegate?
#IBAction func didTap(_ sender: Any) {
// on button tap, "send data back"
predictionHomeDelegate?.receiveData(with: "Test")
}
}
// "home" view controller
// NOTE: this DOES include PredictionDelegate
class PredictionViewController: UIViewController, PredictionDelegate {
func receiveData(with data: String) {
print(data)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "predictionSegue") {
if let vc = segue.destination as? PredictionsTableViewController {
// set self as the delegate of the embedded PredictionsTableViewController
vc.predictionHomeDelegate = self
}
}
}
}
Notes:
Do NOT include func receiveData(with data: String) {} in your embedded view controller
Do NOT assign PredictionDelegate to your embedded view controller
You need to hook your segue to the vc itself instead of the cell and use
self.performSegue(withIdentifier: "predictionSegue", sender: nil)
Since these are two separate screens I am not too sure it makes too much sense to have the button on the first view controller that submits data from the second, can the button not just be on the second. If for whatever reason it can't you could pass the data back to the first view controller on segueing back by adding a public variable to the first view controller and adding another prepare method to the second to pass the data back like you have done when adding the delegate.

Pass data from second VC to first VC and also show in textfield Swift4

I'm getting data from second VC to first VC using protocol or delegates, Data is receiving in first VC but the problem is that Data is not showing in Textfield. Here is my Complete Code for understanding. Any Effort is appreciated.
FirstVC class
import UIKit
class firstViewController: UIViewController, UITextFieldDelegate, MyProtocol {
var valueSentFromSecondViewController : String?
#IBOutlet weak var myTextField : UITextField!
override func viewDidLoad() {
super.viewDidLoad()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func myTextFieldACTIONWhenEditingDidBegin(_ sender: Any) {
myTextField.isUserInteractionEnabled = false
let secondVC = self.storyboard?.instantiateViewController(withIdentifier: "secondViewController") as! secondViewController
secondVC.delegate = self
self.navigationController?.pushViewController(secondVC, animated: true)
}
func setResultsAfterEvaluation(valueSent: String) {
self.valueSentFromSecondViewController = valueSent
print(valueSentFromSecondViewController!) // Ahtazaz(DATA showing here)
myTextField.text = valueSentFromSecondViewController //This's the problem, Why not showing here in this this TextField
}
}
Now, SecondVC Class
import UIKit
protocol MyProtocol {
func setResultsAfterEvaluation(valueSent: String)
}
class secondViewController: UIViewController {
var delegate : MyProtocol?
var sentValue : String?
override func viewDidLoad() {
super.viewDidLoad()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func btn(_ sender: Any) {
let firstVC = self.storyboard?.instantiateViewController(withIdentifier: "firstViewController") as! firstViewController
self.navigationController?.pushViewController(firstVC, animated: true)
sentValue = "Ahtazaz"
delegate?.setResultsAfterEvaluation(valueSent: sentValue!)
}
}
You are pushing SecondVC. Then in SecondVC you are pushing again FirstVC.
I think this is where you are making mistake.
let firstVC = self.storyboard?.instantiateViewController(withIdentifier: "firstViewController") as! firstViewController
You are creating a new instance of FirstVC. Then you push it which is wrong. Call your delegate and then Pop back to previous(FirstVC) controller
Try this code in your button action
#IBAction func btn(_ sender: Any) {
sentValue = "Ahtazaz"
delegate?.setResultsAfterEvaluation(valueSent: sentValue!)
self.navigationController?.popViewController(animated: true)
}
This should be the correct approach rather than pushing the controller again.
The steps are Simple to use Delegates for passing the data to previous VC
Second VC:
At the top of VC declare the protocol as follows:
protocol MenuListingDelegate {
func callBackOfMenuSelected(arrSelectedCategory:[Int],isFromWhichPopup:Int)
}
Then inside that define the variable like this
var delegate:MenuListingDelegate?
And then provide the data to the delegate like this. In my case i provide that on click of button before pop View Controller
self.delegate?.callBackOfMenuSelected(strToPass: "Hello")
Now in First VC:
At the top define the Delegate method like this:
class DayDetailVC: UIViewController,MenuListingDelegate {}
And fetch the Data like this
//MARK:- Menu Listing Delegate
func callBackOfMenuSelected(strToPass: String) {
print(strToPass)
}
Note:- Do not forget to declare the delegate of the secondVC where we use this. secondVC.delegate = self.
Edit Check the following cases
Case 1:- Check the outlets of the myTextField i guess the issue is there. If everything is correct remove the Outlet and the set that again
Case 2:- Still if doesnt work then try setting like this
func setResultsAfterEvaluation(valueSent: String) {
myTextField.text = "\(valueSent)"
}
Hope this helps.
Edit 2
I have seen you have used pushViewController in the following lines:
So you can simply use the following line of code to pass the data to firstVC
In SecondVC add following Code:
let firstVC = self.storyboard?.instantiateViewController(withIdentifier: "firstViewController") as! firstViewController
firstVC.valueSentFromSecondViewController = "Hello World"
self.navigationController?.pushViewController(firstVC, animated: true)
Now in FirstVC
Use like in viewDidLoad() or anywhere you want
print(valueSentFromSecondViewController) //Hello World
Cheers it Done.
Choose the way you want.
Note:- But i will suggest you to use popViewController instead of
pushViewController when returning back from SecondVC -> FirstVC. Rest depends upon your requirements.
Hope this helps.

Can't pass values in UIStoryBoard segue [duplicate]

This question already has answers here:
Swift pass data through navigation controller
(8 answers)
Closed 4 years ago.
I need to send bool value to Second viewController based on some condition.
but in Second ViewController the value of bool variable is always false.
This is First ViewController code:
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
#IBAction func moveTo(_ sender: Any) {
self.performSegue(withIdentifier: "Move2", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if segue.identifier == "Move2"
{
let secondVC = segue.destination as? SecondViewController
secondVC?.second = true
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
The SecondViewController code is
import UIKit
class SecondViewController: UIViewController {
var second = Bool()
override func viewDidLoad() {
super.viewDidLoad()
print(second)
// Do any additional setup after loading the view.
}
But this Value of second variable is false.
Whats wrong in my code. need help. TIA..
EDIT : In both ViewController i have navigation controller. That's problem. SecondVC is SecondViewController's navigation controller, so that i can't pass data to that secondVC.
Go to your Storyboard and select SecondViewController (the yellow circle on the top left. Go to identity inspector and select SecondViewController from the Class drop down.
See image below:
Keep things simple and clean :
FirstVC :
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if segue.identifier == "Move2"
{
let secondVC = segue.destination as? SecondViewController
secondVC.second = true
}
}
SecondVC :
class SecondViewController: UIViewController {
var second: Bool = false
override func viewDidLoad() {
super.viewDidLoad()
print(second)
}
}
Just tested this myself. true is printed.

Pass data to TabBar Controller

I want pass data between two ViewControllers throw the TabBarController.
Inside the first ViewController I located textField and button.
Inside the second I located Label.
When I write some text in textField and push button, I expect that this text appear in the Label in the second ViewController. But nothing happens.
And my code:
First ViewController:
import UIKit
class FirstViewController: UIViewController {
#IBOutlet weak var textField: UITextField!
#IBAction func enter(_ sender: Any) {
if textField.text != "" {
if let window = UIApplication.shared.delegate?.window, let tabBarController = window?.rootViewController as? UITabBarController, let second = tabBarController.viewControllers?.first as? SecondViewController {
second.label.text = textField.text
tabBarController.selectedIndex = 0
}
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
Second ViewController:
import UIKit
class SecondViewController: UIViewController {
#IBOutlet weak var label: UILabel!
var myString = String()
override func viewDidLoad() {
super.viewDidLoad()
label.text = myString
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
I think the problem is in
tabBarController.viewControllers?.first as? SecondViewController
You probably want to do this instead:
tabBarController.viewControllers?[1] as? SecondViewController
Don't forget arrays are indexed from 0, so viewControllers?[1] actually returns the second element in the array.
I'm not recommending that you do it this way. This is an explanation for understanding.
The viewControllers in a tabBarController know their tabBarController. You can access it with self.tabBarController.
The secondViewController is the second one in the list of viewControllers so let second = tabBarController.viewControllers?[1] as? SecondViewController.
If you haven't visited the secondViewController yet, its view will not have loaded, so the outlets will still be nil. You can force the view to load with _ = second.view.
If you want to switch to the second tab, then you need to use tabBarController.selectedIndex = 1.
#IBAction func enter(_ sender: Any) {
if textField.text != "" {
if let tabBarController = self.tabBarController as? UITabBarController, let second = tabBarController.viewControllers?[1] as? SecondViewController {
// make sure view has loaded
_ = second.view
second.label.text = textField.text
// change to second tab
tabBarController.selectedIndex = 1
}
}
}
A better way...
Instead of setting the outlet directly, you should instead pass the string to a property of the SecondViewController:
second.myString = textField.text ?? ""
and then assign that string to the label in an override of viewWillAppear.
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
label.text = myString
}
The reason to set it in viewWillAppear is that viewWillAppear will run every time before the view is displayed. viewDidLoad will only run once when the view is first loaded. Since you want the functionality to work multiple times, viewWillAppear is the correct override.
First i think your view controllers that are representing tabs should be embedded into navigation controllers which would then be linked to the TabBarController.
Secondly, the preferred and recommended way to send data between controllers is through protocols (delegates). Here is a good example you can check out, step by step: https://medium.com/#jamesrochabrun/implementing-delegates-in-swift-step-by-step-d3211cbac3ef
However if you're looking for a quick fix of your solution i think that Bruno Phillipe's answer gets it to some extent, but not quite. We can't really be sure what controller is at what index in the view controller list. I think this should work:
#IBAction func enter(_ sender: Any) {
if textField.text != "" {
if let window = UIApplication.shared.delegate?.window, let tabBarController = window?.rootViewController as? UITabBarController {
//check if there are view controllers in the tabBarController
guard let vcList = tabBarController.viewControllers else {
return
}
for controller in vcList {
if let second = controller as? SecondViewController {
//this will be executed only when a controller is SeconfViewController
second.label.text = textField.text
tabBarController.selectedIndex = 0
}
}
}
}
}
EDIT:
I tried it myself and the problem is that you were trying to set the label.text when in fact the label component was never initialised. I think if you simply stored the textField value into myString variable in SecondViewController it would work (not sure).
However here's the solution using a protocol (delegate) which is the right way to send data between controllers. Ask any questions you might have. This should work:
FirstViewController:
import Foundation
import UIKit
protocol LabelChangeDelegate: class {
func changeLabelWithText(_ text: String?)
}
class FirstViewController: UIViewController {
weak var delegate: LabelChangeDelegate?
#IBOutlet weak var textField: UITextField!
#IBAction func enter(_ sender: UIButton) {
if textField.text != "" {
if let window = UIApplication.shared.delegate?.window, let tabBarController = window?.rootViewController as? UITabBarController {
//check if there are view controllers in the tabBarController
guard let vcList = tabBarController.viewControllers else {
return
}
for controller in vcList {
if let second = controller as? SecondViewController {
//this will be executed only when a controller is SeconfViewController
//set the delegate - who needs the data
delegate = second
//call the delegate function which will commmunicate with the delegate
delegate?.changeLabelWithText(textField.text!)
//don't know why you need this
tabBarController.selectedIndex = 0
}
}
}
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
SecondViewController:
import Foundation
import UIKit
class SecondViewController: UIViewController, LabelChangeDelegate {
#IBOutlet weak var label: UILabel!
//lazy init
lazy var myString = String()
override func viewDidLoad() {
super.viewDidLoad()
//set label when the view loads, not in the first controller
label.text = myString
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//delegate function
func changeLabelWithText(_ text: String?) {
guard let sentText = text else {
//no text sent
return
}
myString = sentText
}
}

how to send data from popover view controller to main view controller. Pass a string so that i can make that as the label text in the main view

I tried many methods to send data from my popup view controller to main view controller. but failed. can anybody help me with this.
i am using a "present as popover" segue. i want to the text entered in textfield of popover view as the label text of main view.
From Popup View, Data send to Main ViewController using protocol in Swift 3.
enter image description here
Complete Details are given below...
1. View Controller Implementing with Protocol named sendDataToViewProtocol.
import UIKit
class ViewController: UIViewController,sendDataToViewProtocol {
#IBOutlet weak var lshowDataLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func btnShowPopUpDialog(_ sender: Any) {
let popUpVc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "PopupVIewController") as! PopupVIewController
//Don't forget initialize protocal deletage
popUpVc.delegate = self
self.addChildViewController(popUpVc)
popUpVc.view.frame = self.view.frame
self.view.addSubview(popUpVc.view)
popUpVc.didMove(toParentViewController: self)
}
func inputData(data: String) {
lshowDataLabel.text = data
}
}
Popup View Controller With Protocol named sendDataToViewProtocol below.
3.protocol declare outside the PopupVIewController.
Don't forget to assign ViewController to PopupVIewController .
In viewController withIdentifier: "PopupVIewController" , "PopupVIewController" is PopupVIewController storyborad Id.
Please see the attached image.
import UIKit
protocol sendDataToViewProtocol {
func inputData(data:String)
}
class PopupVIewController: UIViewController {
//Protocol object
var delegate:sendDataToViewProtocol? = nil
#IBOutlet weak var txtInputFieldText: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = UIColor
.black.withAlphaComponent(0.8)
}
#IBAction func btnSendDataToViewController(_ sender: Any) {
//"Check Delegate nil"
if(delegate != nil){
//Check textField is empty
if(txtInputFieldText.text != ""){
//set textField Data to protocol Function
delegate?.inputData(data: txtInputFieldText.text!)
self.view.removeFromSuperview()
}
}
}
#IBAction func btnClose(_ sender: Any) {
self.view.removeFromSuperview()
}
}
First of all, keep a temporary variable in your Main ViewController. Let's call it:
var somethingCool: String?
Then, in your popup ViewController code, assuming you have your segue trigger there, you will need to add in a new method.
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "your_segue_identifier" {
if let vc = segue.destination as? MainViewController {
vc.somethingCool = "whatever_you_want"
}
}
}

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