i am trying to send an image from my collectionViewCell imageView to an imageView in another VC through delegation and Protocol. I cannot figure out why this isn't working properly?
The sending VC is: TrainersViewController
The recieving VC is: BioViewController
Here is my protocol:
protocol TrainersViewControllerDelegate: class {
func trainersViewController(controller: TrainersViewController, didFinishSendingImage trainer:TrainerArray)
}
class TrainersViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate, AddNewTrainerViewControllerDelegate {
weak var delegate: TrainersViewControllerDelegate?
}
Here is my Receiving class:
class BioViewController: UIViewController, TrainersViewControllerDelegate {
#IBAction func backToTrainersButton(sender: AnyObject) {
dismissViewControllerAnimated(true, completion: nil)
}
override func viewDidLoad() {
super.viewDidLoad()
}
#IBOutlet weak var bioImage: UIImageView!
func trainersViewController(controller: TrainersViewController, didFinishSendingImage trainer: TrainerArray) {
trainer.trainerImage! = bioImage as! UIImage
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "bioSegue" {
let navigationController = segue.destinationViewController as! UINavigationController
let controller = navigationController.topViewController as! TrainersViewController
controller.delegate = self
}
}
}
Finally here is the button within the collectionViewCell that i am calling upon to make this happen:
#IBAction func bioSegueButton(sender: AnyObject) {
let index = sender.tag
let trainer = trainers[index]
print(trainer.name)
delegate?.trainersViewController(self, didFinishSendingImage: trainer)
performSegueWithIdentifier("bioSegue", sender: self)
}
Why is this not sending my image across into the imageView of the other VC?
At the time when you call
delegate?.trainersViewController(self, didFinishSendingImage: trainer)
the variable delegate isn't set yet. You can check this with the following line:
print(delegate)
If the delegate isn't set, then this line will print nil
You can just pass image in prepareForSegue and that would be simplest way (but you have to implement it in sending class). The previous answer is correct. You use it before you set delegate. If you really want to use it i would first perform the segue where when preparing for it you set the delegate and then try to use delegate method.
#IBAction func bioSegueButton(sender: AnyObject) {
let index = sender.tag
let trainer = trainers[index]
print(trainer.name)
performSegueWithIdentifier("bioSegue", sender: self)
delegate?.trainersViewController(self, didFinishSendingImage: trainer)
}
It could cause another problem but it would be not about delegation :)
You could try reversing your delegation. In BioViewController make BioViewControllerDelegate with method bioViewControllerSetUpImage(bioViewController: BioViewController) -> UIImage implement it in sending class and call it in BioViewController class for example in viewDidLoad like bioImage = delegate?.bioViewControllerSetUpImage(self). Then you create BioViewController, set delegate, segue. (But this is my attempt to work it around, feel free to ignore it)
Related
I have 2 Controllers: MainVC and SideMenuVC.
I wanted to modify MainVC using SideMenuVC, so created delegate of SideMenuVC ( as well, there's Emdebed segue "name..." to "Side Menu View Controller" on storyboard because MainViewController has subView, which contains ContainerView - this container is our SideMenuVC. And this delegate works as he should.
However, due to logic in the app, I also need to send data from MAINVC to SIDEMENUVC.
So i did the same - created another delegate of second VC... But I turned out, MainViewControllerDelegate is not responding in SideMenuViewController. And i'm absolutely clueless...
Yes, i do implement necessary protocols in both classes, in extension!
Code of both VCs below, screens of storyboard in the attachment
MainViewController + MainViewControllerDelegate
protocol MainViewControllerDelegate{
func isImageLoaded(_ isLoaded:Bool)
}
class MainViewController: UIViewController {
/* ... */
var delegate: MainViewControllerDelegate?
var sideMenuViewController: SideMenuViewController?
private var isSideMenuPresented:Bool = false
private var isImageLoaded:Bool = false
override func viewDidLoad() {
super.viewDidLoad()
self.isImageLoaded = false
self.setupUI()
self.delegate?.isImageLoaded(false)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "MainVC_SideMenuVC_Segue")
{
if let controller = segue.destination as? SideMenuViewController
{
self.sideMenuViewController = controller
self.sideMenuViewController?.delegate = self
}
}
}
/* ... */
//I'm using PHPicker, and when new image is selected, i want to send "true" via delegate
func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
dismiss(animated: true)
if let itemProvider = results.first?.itemProvider, itemProvider.canLoadObject(ofClass: UIImage.self){
let previousImage = self.presentedImage.image
itemProvider.loadObject(ofClass: UIImage.self){ [weak self] image, error in
DispatchQueue.main.async {
guard let self = self, let image = image as? UIImage, self.presentedImage.image == previousImage else {
return
}
self.presentedImage.image = image
self.isImageLoaded = true;
self.delegate?.isImageLoaded(true)
}
}
}
}
SideMenuViewController + SideMenuViewControllerDelegate
protocol SideMenuViewControllerDelegate{
func hideSideMenu()
func performAction(_ type:OperationType)
}
class SideMenuViewController: UIViewController {
/*...*/
var delegate: SideMenuViewControllerDelegate?
var mainViewController: MainViewController?
private var menuData: [ExpandingCellModel] = []
private var isImageLoaded: Bool = false
override func viewDidLoad() {
super.viewDidLoad()
// self.mainViewController?.delegate = self
menuData = setupData()
setupUI()
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let controller = segue.destination as? MainViewController {
controller.delegate = self
}
}
}
/* ... */
Here is what I think is happening.
There is segue happening from MainVC to SideMenuVC but there is no segue actually happening between SideMenuVC to MainVC in my opinion.
Happening is keyword because there is an EmbedSegue from MainVC to SideMenuVC but where is the segue from SideMenuVC to MainVC ? You did some connection in storyboard but nothing is happening in my opinion.
That is why in override func prepare is being called as planned in MainViewControllerDelegate and the delegate is getting set but it is not getting set in SideMenuViewController since override func prepare doesn't get called as no segue happens.
What you can do instead which might work is set both the delegates inside prepare in MainViewControllerDelegate
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "MainVC_SideMenuVC_Segue")
{
if let sideMenuVC = segue.destination as? SideMenuViewController
{
sideMenuVC.delegate = self
// assign MainViewControllerDelegate here
self.delegate = sideMenuVC
}
}
}
Check now if data is sent back to main view controller also.
If your issue is still not yet solved, please have a look and try this small example I set for you in github to show passing data between mainVC and embeddedVC and it might give you some hints.
You can see the result of this in action here: https://youtu.be/J7C7SEC04_E
I've got two View Controllers. Main and Temporary one. The second one performs an action on the different screen (is called by pushViewController) and then I'm popping (popViewController) and would like to present the returned value which is String.
I've tried using protocol but it's nil.
Here is my code:
SecondVC.swift:
protocol ValueDelegate {
func append(_ text: String)
}
class SecondViewController: UIViewController{
var delegate: ValueDelegate!
...
...
private func function(){
if let delegate = self.delegate{
delegate.append(value.stringValue)
}
navigateBack()
}
private func navigateBack(){
if let navigation = self.navigationController{
navigation.popViewController(aniamted: true)
}
}
MainVC.swift:
class MainViewController: UIViewController, ValueDelegate {
var secondVC = SecondViewController()
...
func append(_ value: String) {
textField.text?.append(barcode)
}
...
override func viewDidLoad(){
super.viewDidLoad()
self.secondVC.delegate = self
}
}
Use these links to understand exactly how to use Protocols in swift:
Passing data between two ViewControllers (delegate) - Swift
Passing Data between View Controllers
You have to implement below line of code in first view controller :-
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showSecondViewController" {
let secondViewController = segue.destination as! SecondViewController
secondViewController.delegate = self
}
}
I've tried using protocol but it's nil.
Because you never set it to anything. It was your job, when you pushed the SecondViewController, to set its valueDelegate to the MainViewController. But you didn't.
What you did do was set the valueDelegate of another SecondViewController to the MainViewController:
var secondVC = SecondViewController()
self.secondVC.delegate = self
That was silly, because secondVC is a different, newly made instance of SecondViewController having nothing at all to do with your real interface. In particular, it is not the SecondViewController instance that gets pushed. But that is the instance you need to set the delegate of.
I know the same question is asked many times. I read most of the answers from stack overflow and tried. But it did not help my problem.
I have two view controllers
protocol UpdateDataDelegate {
func loadData()
}
viewcontroller2 {
var delegate: UpdateDataDelegate?
override func viewDidLoad() {
super.viewDidLoad()
}
fun saveData() {
self.delegate?.loadData()
}
}
viewcontroller1 : UpdateDataDelegate {
var vc2 = viewcontroller2()
override func viewDidLoad() {
super.viewDidLoad()
vc2.delegate = self
}
func loadData() {
}
}
But function loadData() from viewcontroller1 is not called.
Since I don't have the complete code before me I can only assume that the delegate is not assumed properly.
If the delegate is not initialised properly it cannot pass value to the other viewController.
You can check delegate is properly initialised by:
if let delegate = delegate{
//Do your works here
}else{
print("The delegate is nil")
}
if the delegate is nil is printed in console, then the problem might be in the way the delegate was initialised
This might be because you are setting the delegate and opening an another instance of the viewController which was not assigned the delegate value.
In the code you provided I see that you are setting the delegate as
var vc2 = viewcontroller2()
vc2.delegate = self
But I cannot see the code that you used to move to the viewController2. Now we have to present this assigned viewController. Instead of using segue to move to the viewcontroller2 present this vc using the code below
present(vc2, animated: true, completion: nil)
You should place this according to your code logic.(where your segue is triggered)
Situation 2:
If you are using segue to move to the viewController2 then the delegate should be assigned in the prepareforSegue method as below
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let vc2 = segue.destination as? ViewController2{
vc2.delegate = self
}
}
let me know how it goes.
A simple playground for what you are trying to do, even if I have not clear what you are trying to achieve:
import UIKit
protocol UpdateDataDelegate: class {
func loadData()
}
class ViewController2: UIViewController {
weak var delegate: UpdateDataDelegate?
func saveData() {
self.delegate?.loadData()
}
}
class ViewController1: UIViewController {
}
extension ViewController1: UpdateDataDelegate {
func loadData() {
print("loadData called")
}
}
let viewController1 = ViewController1()
let viewController2 = ViewController2()
viewController2.delegate = viewController1
viewController2.saveData()
Few notes:
classes should be upper case. So, ViewController1 instead viewcontroller1
delegates should be weak otherwise you create reference cycles
class should be used for UpdateDataDelegate protocol otherwise compiler will complain since weak cannot be applied to class and class-bound protocol types
prefer extension to conform to protocols. It makes the code easy to read
The only thing I see missing in your code is call to saveData() of ViewController2 that will in turn call loadData() of ViewController1.
So just add:
override func viewDidLoad()
{
super.viewDidLoad()
vc2.delegate = self
vc2.saveData() //Add this line to your code
}
You are good to go now :)
Edit:
protocol UpdateDataDelegate
{
func loadData()
}
class ViewController2: UIViewController
{
var delegate: UpdateDataDelegate?
func saveData()
{
self.delegate?.loadData()
}
}
class ViewController1: UIViewController, UpdateDataDelegate
{
var vc2 = ViewController2()
override func viewDidLoad()
{
super.viewDidLoad()
vc2.delegate = self
vc2.saveData()
}
func loadData()
{
print("Done")
}
}
I have used the above code and it is working fine for me. How are you executing it? I have used storyboard and used ViewController1 as the Initial View Controller.
I assume that you need to load data when your delegate has been set up. In this case you can use magic didSet:
weak var delegate: UpdateDataDelegate? {
didSet {
self.saveData()
}
}
So right after setting the delegate the needed method will be called.
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"
}
}
}
How can I pass data back from a PopoverViewController to the main view controller on an iPhone?
I know I'm doing something terribly wrong but I cannot figure it out.
Here is the code:
PopoverViewController.swift
protocol PopoverViewControllerDelegate {
func messageData(data: AnyObject)
}
class PopoverViewController: UIViewController {
#IBOutlet weak var inputMessage: UITextField!
var delegate: PopoverViewControllerDelegate?
#IBAction func sendData(sender: AnyObject) {
if inputMessage.text != ""{
self.presentingViewController!.dismissViewControllerAnimated(true, completion: nil)
self.delegate?.messageData(inputMessage.text!)
}
}
}
Main ViewController.swift:
class ViewController: UIViewController, UIPopoverPresentationControllerDelegate, PopoverViewControllerDelegate {
#IBOutlet weak var showData: UILabel!
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// popover segue
if segue.identifier == "popoverSegue" {
let popoverViewController = segue.destinationViewController
popoverViewController.popoverPresentationController!.delegate = self
}
// code to comunicate with data in popoverViewController
let pvc = storyboard?.instantiateViewControllerWithIdentifier("popoverViewController") as! PopoverViewController
pvc.delegate = self
self.presentViewController(pvc, animated:false, completion:nil)
}
func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
return UIModalPresentationStyle.None
}
func messageData(data: AnyObject) {
self.showData.text = "\(data)"
}
}
With the code above I can pass data back to the main view controller without a problem, the issue is that the popover doesn't work, it just acts like a regular ViewController occupying the whole screen.
The funny thing is that if I comment the following line of code the popover works but I can no longer pass data back, I can see the popover but the passing data stops working.
// if I comment this line
self.presentViewController(pvc, animated:false, completion:nil)
I don't get any errors, one just stops working.
Any suggestions?
Thanks a lot
In prepareForSegue, the destinationViewController is your PopoverViewController. You need to cast it to that and set the delegate on that so that you can pass back data, and you need to set the popoverPesentationController?.delegate as well. You don't need the rest of the code in prepareForSegue:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// popover segue
if segue.identifier == "popoverSegue" {
let popoverViewController = segue.destinationViewController as! PopoverViewController
popoverViewController.delegate = self
popoverViewController.popoverPresentationController?.delegate = self
}
}