I am trying to change lable of one view controller from another view controller using custom protocol but its delegate method is not being called
ViewController3 code:
when i click on close button it's delegate method is not being called in my ViewController2.
protocol ViewController3Delegate: class {
func changeLable(_ text: String)
}
class ViewController3: UIViewController {
weak var delegate: ViewController3Delegate?
override func viewDidLoad() {
super.viewDidLoad()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
#IBAction func btnCloseAction(_ sender: Any) {
delegate?.changeLable("fillter applied")
self.dismiss(animated: true, completion: nil)
}
}
ViewController2 code:
class ViewController2: UIViewController,ViewController3Delegate {
#IBOutlet weak var lblReport: UILabel!
let VC3 = ViewController3(nibName: "ViewController3", bundle: nil)
override func viewDidLoad() {
super.viewDidLoad()
VC3.delegate = self
}
func changeLable(_ text: String) {
print("delegate called")
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
Anybody knows where i am wrong, please suggest me some solution
You have not defined a delegate in your ViewController2 which will be used to the delegate in ViewController3 .
See This :
protocol ViewController3Delegate: class {
func changeLable(_ text: String)
}
class ViewController3: UIViewController {
weak var delegate: ViewController3Delegate?
override func viewDidLoad() {
super.viewDidLoad()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
#IBAction func btnCloseAction(_ sender: Any) {
if delgate !=nil {
delegate?.changeLable("fillter applied")
self.dismiss(animated: true, completion: nil)
}
}
}
And then in your ViewController2 class :
class ViewController2: UIViewController,ViewController3Delegate {
#IBOutlet weak var lblReport: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
func changeLable(_ text: String) {
print("delegate called")
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if segue.identifier = "Yoursegueientifier"
{
let vc = segue.destination as! ViewController3
vc.delegate = self
}
}
}
Note : You have to define your segueidentifer name in your storyboard
You should first present ViewController3 from ViewController2 like this:
let VC3 = ViewController3(nibName: "ViewController3", bundle: nil)
VC3.delegate = self
self.presentViewController(VC3, animated: true, completion: nil)
Also, you can delete this line above viewDidLoad
let VC3 = ViewController3(nibName: "ViewController3", bundle: nil)
Related
I have two view controllers A,B in controller scenes. I can create a segue from A -> B.
I also create an unwind segue from B -> A with a prepare function.
This function is being executed but the value is not being passed to passedDataString is not being passed back.
import UIKit
class homeViewController: UIViewController , UIAlertViewDelegate {
#IBOutlet weak var returnStatusLbl: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
var passedDataString = "QR Return not set"
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
returnStatusLbl.text = passedDataString
}
#IBAction func QRtoHome( _ sender: UIStoryboardSegue) {}
}
import UIKit
class QRViewController: UIViewController {
#IBOutlet weak var wherefromLbl: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let destVC = segue.destination as! homeViewController
destVC.passedDataString = "From Done"
}
}
When you return by unwind, viewWillAppear is not called.
You could use an observer:
var passedDataString : String = "QR Return not set" {
didSet {
returnStatusLbl.text = passedDataString
}
}
I found this works:
#IBAction func QRtoHome( _ sender: UIStoryboardSegue) {
returnStatusLbl.text = passedDataString
}
enter image description herei am making a program with delegate protocol in which we add value in text field in second controller and click save and this value is set to the label in the previous viewController
all the this are done but the value can not set to the label
Can someone please explain me what is triggering the messageData() method in the main ViewController?
import UIKit
protocol SenderViewControllerDelegate {
func messageData(data: String)
}
class NewViewController: UIViewController {
//MARK:- Properties
#IBOutlet weak var firstTextField: UITextField!
var delegate: SenderViewControllerDelegate?
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 SaveFirstValue(_ sender: Any) {
if delegate != nil{
if firstTextField.text != nil{
let data = firstTextField.text
delegate?.messageData(data: data!)
dismiss(animated: true, completion: nil)
}
}
}
}
import UIKit
class ViewController: UIViewController,SenderViewControllerDelegate {
//MARK:- Properties
#IBOutlet var firstLabel: UILabel!
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.
}
//MARK:- Actions
func messageData(data: String) {
firstLabel.text = data
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showSendingVc" {
let viewController : ViewController = segue.destination as! NewViewController
ViewController.delegate = self
}
}
}
Change this line
let viewController = segue.destination as! NewViewController
viewController.delegate = self
`ViewController.delegate = self` should be `viewController.delegate = self`
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showSendingVc" {
let viewController : NewViewController = segue.destination as! NewViewController //destination is type NewViewController not ViewController
// ViewController.delegate = self //Wrong
viewController.delegate = self
}
}
You made mistake in the line ViewController.delegate = self it should be
viewController.delegate = self
means small "v" (object of ViewController)
UPDATED:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showSendingVc" {
let objectOfVC = segue.destination as! NewViewController
objectOfVC.delegate = self
}
}
In ViewController Class set the delegate inside ViewDidLoad method like this:
newViewControllerObj. delegate = self
Without calling viewController Class, the delegate will not set So you have to call ViewController class inside NewViewController or other class which will call first like that:
let ViewControllerObj = ViewController()
I want to the image thats in my UIImageView on my previous View after I tap on a button.
Any help? Thanks.
MainViewController.swift
class MainViewController: UIViewController {
#IBOutlet weak var hatBackground: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
hatBackground.image = UIImage(named: "black-hat-front.jpg")
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showPatches"{
if let childViewController = segue.destination as? ChildViewController{
}
}
}
}
ChildViewController.swift
class ChildViewController: UIViewController {
#IBOutlet weak var doubleCupButton: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
self.title = "Choose a Patch"
}
#IBAction func doubleCupButtonPressed(_ sender: AnyObject) {
hatBackground.image = UIImage(named: "badgal-hat.jpg")??
// Go back to previous Controller
navigationController?.popViewController(animated: true)
}
}
If I good understood , you want choose image in ChildViewController and show it in MainViewController. To do that you should implement delegate pattern like this:
MainViewController
class MainViewController: UIViewController, ChildViewControllerDelegate {
#IBOutlet weak var hatBackground: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
hatBackground.image = UIImage(named: "black-hat-front.jpg")
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showPatches"{
if let childViewController = segue.destination as? ChildViewController{
childViewController.delegate = self
}
}
}
func didSelectImage(image: UIImage?) {
self.hatBackground.image = image
}
}
ChildViewController
class ChildViewController: UIViewController {
#IBOutlet weak var doubleCupButton: UIButton!
var delegate: ChildViewControllerDelegate?
override func viewDidLoad() {
super.viewDidLoad()
self.title = "Choose a Patch"
}
#IBAction func doubleCupButtonPressed(_ sender: AnyObject) {
let selectedImage = UIImage(named: "badgal-hat.jpg")
delegate?.didSelectImage(image: selectedImage)
self.navigationController?.popViewController(animated: true)
}
}
ChildViewControllerDelegate
protocol ChildViewControllerDelegate {
func didSelectImage(image:UIImage?)
}
I have the following:
class Settings: UIViewController {
#IBAction func CitySend(sender: AnyObject) {
self.performSegue(withIdentifier: "senddata", sender: self)
}
#IBOutlet weak var textField: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "senddata" {
let Mainview = segue.destination as! ViewController
Mainview.label = textField.text!
}
}
}
My mainview looks like this:
class ViewController: UIViewController {
#IBOutlet var city: UILabel!
var label: String = ""
override func viewDidLoad() {
super.viewDidLoad()
city.text = label
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
im not sure, if this is how i should even do this, but to me the logic is that i only want to allow this segue to pass a string to my label in my mainview if the button is pressed (Like a save button)
However as to what i have made now, nothing happens, and it gives me the 1: signal SIGABRT error, whenever i press the button.
Use the following code:
ViewController.swift
import UIKit
class ViewController: UIViewController, SecondViewControllerProtocol{
#IBOutlet weak var dataLabel: UILabel!
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.
}
#IBAction func navigateToSecondViewControllerOnButtonClick(_ sender: AnyObject) {
let secondVC: ViewController2 = storyboard?.instantiateViewController(withIdentifier: "viewcont2") as! ViewController2
secondVC.delegate = self
self.navigationController?.pushViewController(secondVC, animated: true)
}
func saveData(data: String){
dataLabel.text = data
}
}
ViewController2.swift
import UIKit
protocol SecondViewControllerProtocol {
func saveData(data: String) // this function the first controllers
}
class ViewController2: UIViewController {
var delegate: SecondViewControllerProtocol?
#IBOutlet weak var dataTextField: UITextField!
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 saveButtonClicked(_ sender: AnyObject) {
delegate?.saveData(data: dataTextField.text!)
}
}
Storyboard screenshot:
Please check my GitHub link below to test sample:
https://github.com/k-sathireddy/PassingDataThroughSegue
#IBAction func CitySend(sender: AnyObject) {
self.performSegue(withIdentifier: "senddata", sender: textField.text)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
switch (segue.identifier, segue.destination, sender) {
case (.Some("senddata"), let controller as ViewController, let text as String):
controller.label = text
default:
break
}
}
My code is below. When I press the 'Done' or 'Cancel' buttons, it doesn't work as I want. I did some debugging, and delegate is nil even though I set it. Please help - thanks.
class ViewController: UIViewController,EditViewControllerDelegate {
#IBOutlet weak var label: UILabel!
//页面跳转时
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "EditView" {
//通过seque的标识获得跳转目标
let controller = segue.destinationViewController as! EditViewController
//设置代理
controller.delegate = self
//将值传递给新页面
controller.oldInfo = label.text
}
}
func editInfo(controller:EditViewController, newInfo:String){
label.text = newInfo
//关闭编辑页面
controller.presentingViewController!.dismissViewControllerAnimated(true, completion: nil)
}
func editInfoDidCancer(controller:EditViewController){
//关闭编辑页面
controller.presentingViewController!.dismissViewControllerAnimated(true, completion: nil)
}
}
import UIKit
protocol EditViewControllerDelegate {
func editInfo(controller:EditViewController, newInfo:String)
func editInfoDidCancer(controller:EditViewController)
}
class EditViewController: UIViewController {
#IBOutlet weak var textField: UITextField!
var delegate:EditViewControllerDelegate?
var oldInfo:String?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
if oldInfo != nil{
textField.text = oldInfo
}
}
#IBAction func done(sender: AnyObject) {
delegate?.editInfo(self, newInfo: textField.text!)
}
#IBAction func cancel(sender: AnyObject) {
delegate?.editInfoDidCancer(self)
}
}
Try this,
class ViewController: UIViewController,EditViewControllerDelegate {
var controller: EditViewController?
#IBOutlet weak var label: UILabel!
//页面跳转时
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "EditView" {
//通过seque的标识获得跳转目标
controller = segue.destinationViewController as! EditViewController
//设置代理
controller.delegate = self
//将值传递给新页面
controller.oldInfo = label.text
}
}
func editInfo(controller:EditViewController, newInfo:String){
label.text = newInfo
//关闭编辑页面
controller.presentingViewController!.dismissViewControllerAnimated(true, completion: nil)
}
func editInfoDidCancer(controller:EditViewController){
//关闭编辑页面
controller.presentingViewController!.dismissViewControllerAnimated(true, completion: nil)
}
}
import UIKit
protocol EditViewControllerDelegate {
func editInfo(controller:EditViewController, newInfo:String)
func editInfoDidCancer(controller:EditViewController)
}
class EditViewController: UIViewController {
#IBOutlet weak var textField: UITextField!
var delegate:EditViewControllerDelegate?
var oldInfo:String?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
if oldInfo != nil{
textField.text = oldInfo
}
}
#IBAction func done(sender: AnyObject) {
delegate?.editInfo(self, newInfo: textField.text!)
}
#IBAction func cancel(sender: AnyObject) {
delegate?.editInfoDidCancer(self)
}
}
I’m not able to tell from your code how you are handling the opening of EditViewController from your ViewController.
I’m guessing that your prepareForSegue:sender: is not getting called resulting in the delegate not getting set. To fix this, you will need to add a performSegueWithIdentifier:sender: call at the point where the segue needs to happen as in
self.performSegueWithIdentifier("EditView", sender: self)
You should replace whatever code is performing the opening of EditViewController with that call.
I have an app the uses showViewController:sender: to open up a second view controller from the first one even though there is a Show segue defined in my storyboard. The segue in my storyboard doesn’t get used in that case and prepareForSegue:sender: is never called as a result.
If I replace my
showViewController(myVC, sender: self)
with
performSegueWithIdentifier("mySegue", sender: self)
then prepareForSegue:sender: will get called. If I am setting a delegate, like you are, in prepareForSegue:sender:, the delegate will get set before the segue happens.