I'm developing an app for iPad Pro. In this app, containerView use to add additional views and interact with them.
First, I created a protocol:
protocol DataViewDelegate {
func setTouch(touch: Bool)
}
Then, I created my first view controller
import UIKit
class ViewController: UIViewController, DataViewDelegate {
#IBOutlet var container: UIView!
#IBOutlet var labelText: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
func setTouch(touch: Bool) {
if touch == true {
labelText.text = "Touch!"
}
}
}
And finally, I created a view that will be embedded in containerView.
import UIKit
class ContainerViewController: UIViewController {
var dataViewDelegate: DataViewDelegate?
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func touchMe(sender: AnyObject) {
dataViewDelegate?. setTouch(true)
}
}
But for some reason, nothing happened, the first view controller receives nothing in setTouch function.
My question is: In this case, using container, how can I make the communication between two ViewsControllers?
Like #nwales said you haven't yet set the delegate. You should do set the delegate in prepareForSegue function on your first viewController (who contain the viewContainer)
First select the embed segue and set an identifier in the attributes inspector.
Then in the parentViewController implement the func prepareForSegue like this:
Swift 4+:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "the identifier") {
let embedVC = segue.destination as! ViewController
embedVC.delegate = self
}
}
Below:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
if (segue.identifier == "the identifier") {
let embedVC = segue.destinationViewController as! ContainerViewController
embedVC.dataViewDelegate = self
}
}
Looks like you defined the delegate, but have not set the delegate. This happens to me all the time.
Related
Struggling to get my viewControllers to send value from the main viewController to a second. I want it to happen on a button click, I'm going to get the value from the button and pass it to the new form. But it just isn't working.
Code for main ViewController
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func butClick(_ sender: UIButton) {
NSLog("Button Pressed : %#",[sender .currentTitle])
//var tt = [sender .currentTitle]
// Create the view controller
let vc = TimesTablesViewController(nibName: "TimesTablesViewController", bundle: nil)
vc.passedValue = "xx"
self.performSegue(withIdentifier: "pushSegue", sender: nil)
}
}
Code for second viewController called TimesTablesViewController:
class TimesTablesViewController: UIViewController {
#IBOutlet weak var titleLabel: UILabel!
var passedValue:String = ""
override func viewDidLoad() {
super.viewDidLoad()
titleLabel?.text = "\(passedValue) Times Table"
}
}
I've followed tutorials but can't seem to solve the problem! Thanks for any help!
Replace
self.performSegue(withIdentifier: "pushSegue", sender: nil)
with
self.present(vc,animated:true,completion:nil)
or ( if the current vc is inside a naigation )
self.navigationController?.pushViewController(vc,animated:true)
Using
self.performSegue(withIdentifier: "pushSegue", sender: nil)
is fit with storyboards not xibs and if this your case then you need to use the above line only inside the button action with implementing this method inside the source vc
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "pushSegue" {
if let nextViewController = segue.destination as? TimesTablesViewController{
nextViewController.passedValue = "xx"
}
}
}
I’m assuming that the new view controller is appearing, but you’re simply not seeing the data. If so, you’re evidently using storyboards. The TimesTablesViewController(nibName:bundle:) only works if you’re using XIB/NIBs and manually presenting new view controller.
If you’re really using storyboards, simplify your butClick method:
#IBAction func butClick(_ sender: UIButton) {
NSLog("Button Pressed")
performSegue(withIdentifier: "pushSegue", sender: self)
}
But implement prepare(for:sender:):
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destination = segue.destination as? TimesTablesViewController {
destination.passedValue = "xx"
}
}
Assuming the above fixes your problem, I might suggest a further simplification. Notably, if your butClick(_:) method is really only calling performSegue, you can segue to this next scene without any #IBAction method at all:
remove butClick(_:) entirely;
remove the connection between the button and the butClick method in IB, on the “Connections Inspector” tab in the right panel; and
control-drag from the button previously hooked up to butClick(_:) to the scene for TimesTablesViewController.
That will simplify your code further.
View controller A
class ViewController: UIViewController {
var delegate: server?
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func ok(_ sender: Any) {
delegate?.datum(data: "sd")
performSegue(withIdentifier: "goingB", sender: self)
}
}
View controller B
protocol server {
func datum(data: String)
}
class ViewControllerB: UIViewController, server {
#IBOutlet weak var label: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
func datum(data: String) {
self.label.text = data
print(data)
}
}
I need to pass the data via view controllers but I cannot able to pass however I know we can pass data through protocols, but anyhow I end up with error when try to run the program
If you need to pass data from one view controller to another and you're using segue for presenting new view controller, you can just override prepare(for:sender:), there is no need to using delegates. Here you can get reference for controller which will be presented and you can assign its variable.
So, first create variable in second view controller and declare that if you assign it with new value, it changes text of your label
class ViewControllerB: UIViewController {
#IBOutlet weak var label: UILabel!
var variable: String? {
didSet {
label.text = variable
}
}
}
Now in first view controller override prepare(for:sender:) and if segue is segue which you've performed, downcast destination view controller and assign its variable
class ViewController: UIViewController {
#IBAction func ok(_ sender: Any) {
performSegue(withIdentifier: "goingB", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goingB" {
let destinationVC = segue.destination as! ViewControllerB
destinationVC.variable = "sd"
}
}
}
Anyway, if you want to use your code with delegate, you have to set delegate of first view controller as second view controller which will be presented. For this purpose you can also use prepare(for:sender:) where you can get reference for destination of segue and then you can call your method on delegate
class ViewController: UIViewController {
var delegate: server?
#IBAction func ok(_ sender: Any) {
performSegue(withIdentifier: "goingB", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goingB" {
let destinationVC = segue.destination as! ViewControllerB
delegate = destinationVC
delegate?.datum(data: "sd")
}
}
}
Notes:
Name protocol with big capital letter Server and we are talking about delegates, add delegate word: ServerDelegate
Constrain protocol for just for classes
Make then your delegate variable weak
protocol ServerDelegate: class {
func datum(data: String)
}
...
weak var delegate: ServerDelegate?
The simplest here is to to set the property directly in prepare.
However, if you want to use delegate, you can. Your problem is that you have mixed between A and B.
The way you wrote it, when you call delegate?.datum, delegate is not defined and we can't access datum.
What do you want to do ? Go from A to B, and when in B, update a label in B with data received from A.
Here just to show how to use (but clearly too complex compared with direct assignment).
protocol Server {
func datum() -> String
}
class ViewControllerB: UIViewController {
#IBOutlet weak var label: UILabel!
var delegate: Server?
override func viewDidLoad() {
super.viewDidLoad()
let data = delegate?.datum()
self.label.text = data
}
}
class ViewControllerA: UIViewController, Server {
override func viewDidLoad() {
super.viewDidLoad()
}
var data = "sd"
func datum() -> String {
return data
}
#IBAction func ok(_ sender: Any) {
performSegue(withIdentifier: "goingB", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destVC = segue.destination as? ViewControllerB {
destVC.delegate = self
}
}
}
I'm absolute newbie in Swift and OSX development, and I'm sorry if my question will be too noob. I want to understand principles of navigation between NSViewControllers.
I have my default ViewController, where are login and password fields and button to login. After click on button, returns token. And now I trying to change "view" to SecondViewController and save somewhere token, I will need it in future. How can I do it? and it possible to do this in function?:
#IBAction func loginButton(_ sender: Any) {
....
}
Thank you!
You need to use segues to perform this action.
First make the segues connections between the ViewControllers using to storyboard editor. After that you need to give the segues an identifier on the storyboard's attributes inspector. Then in your code you can call the new ViewController by the segue like the code below.
With this code you can pass the data using the button:
class ViewController: NSViewController {
var dataToPass: String = "DataToPass"
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func loginButton(_ sender: Any) {
performSegue(withIdentifier: NSStoryboardSegue.Identifier(rawValue: "segueIdentifier"), sender: self)
}
override func prepare(for segue: NSStoryboardSegue, sender: Any?) {
if segue.identifier!.rawValue == "segueIdentifier" {
let destinationViewController = segue.destinationController as! ViewController2
destinationViewController.dataToReceive = dataToPass
}
}
}
class ViewController2: NSViewController {
var dataToReceive: String
override func viewDidLoad() {
super.viewDidLoad()
}
}
And with this code you will use the override viewWillAppear
class ViewController: NSViewController {
var dataToPass: String = "DataToPass"
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewWillAppear() {
performSegue(withIdentifier: NSStoryboardSegue.Identifier(rawValue: "segueIdentifier"), sender: self)
}
override func prepare(for segue: NSStoryboardSegue, sender: Any?) {
if segue.identifier!.rawValue == "segueIdentifier" {
let destinationViewController = segue.destinationController as! ViewController2
destinationViewController.dataToReceive = dataToPass
}
}
}
class ViewController2: NSViewController {
var dataToReceive: String
override func viewDidLoad() {
super.viewDidLoad()
}
}
In both cases you need to assure the data you want to pass to the other view controller is not null.
NOTE: Question has been edited in an attempt to be more clear with my issue.
Hey, I am trying to pass data through multiple VCS. I want to pass data (arrays) from V2 -> V3 and then V3 -> V1 but I want to be able to only navigate through the VCs as such: V1 - V2 - V3 and V3 - V2 - V1.
So what I need to learn is how to pass data without navigating to a different VC as well as setting up two preparetosegue methods to pass data between V2 -> V3 and V3 -> V1 while also being able to navigate between all VCs. When I create my first preparetosegue, I am unable to use other segues associated in my VC to navigate to other VCs without getting a Fatal Error.
Can anyone help me?
Any input would be greatly appreciated!
Heres my attempt:
import UIKit
class ViewController: UIViewController {
var name = String()
var StopButInfo = [String]()
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.
}
}
import UIKit
class SecondViewController: UIViewController {
var StringArray = [String]()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
#IBOutlet var PHeight: UITextField!
#IBOutlet var PName: UITextField!
#IBAction func Search(_ sender: Any) {
if PHeight.text != ""{
performSegue(withIdentifier: "SearchSegue", sender: self)}
let CDstart = String(describing: Date())
StringArray.append(CDstart)
StringArray.append(PName.text!)
StringArray.append(PHeight.text!)
}
override func prepare(for SearchSegue: UIStoryboardSegue, sender: Any?){
let thirdController = SearchSegue.destination as! ThirdViewController
thirdController.SearchButInfo = StringArray
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
import UIKit
class ThirdViewController: UIViewController {
var height = String()
var SearchButInfo = [String]()
var StringArray = [String]()
#IBAction func Stop(_ sender: Any) {
if StringArray.count != 0{
performSegue(withIdentifier: "SegueToStart", sender: self)
}
let CDStop = String(describing: Date())
StringArray.append(CDStop)
StringArray.append(height)
}
override func prepare(for SegueToStart: UIStoryboardSegue, sender: Any?){
let firstController = SegueToStart.destination as! ViewController
firstController.StopButInfo = StringArray}
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.
}
}
You need to check which view controller's segue is about to be performed, this can be done like this inside prepare(for segueMVH: UIStoryboardSegue, sender: Any?) method:
if let firstController = segueMVH.destination as! FirstViewController {
// Set first view controller's data
} else if let secondController = segueMVH.destination as! SecondViewController {
// Set second view controller's data
} else if let thirdController = segueMVH.destination as! ThirdViewController {
// Set third view controller's data
}
Note: It's better to use a different identifier for each segue to be able to distinguish between them.
The error you got on let secondController = segueMVH.destination as! ThirdViewController is saying that you are casing HC.ViewController into ThirdViewController and that's why it failed. It means that the destination view controller of your segue is not ThirdViewController.
To further help you understand segue: A segue is a connection between a source view controller and a destination view controller and can be only used between them two. See this picture:
In this case, I have a segue connection in my storyboard connected between my VC1's button and VC2. In this case, my button click will trigger this segue and prepare(for segue) method can only be in VC1 where it passes data to VC2.
So in your situation, you believe that the destination of your segue is ThirdViewController but it's actually not. So please check your segue with identifier segueMVH to see if it is connected between your current view controller and your ThirdViewController.
Hope this helps
I have a view that has two text fields and a button.
#IBOutlet var inputURL: UITextField!
#IBOutlet var inputName: UITextField!
#IBAction func submitUrlButton(sender: AnyObject) {
}
and a second view that has two variables:
var submittedURL = ""
var submittedName = ""
println("Name \(submittedName)")
println("URL \(submittedURL)")
In Swift How do I pass the values entered in the two text fields and assign them to those variables in the second view?
Thanks
EDIT FOR THETOM:
import UIKit
class ViewController: UIViewController {
#IBOutlet var inputURL: UITextField!
#IBAction func submitBtn(sender: AnyObject) {
performSegueWithIdentifier("submissionSegue", sender: self)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
// Create a new variable to store the instance of the next view controller
let destinationVC = segue.destinationViewController as BrandsViewController
destinationVC.submittedURL.text = inputURL.text
}
}
You can use the method prepareForSegue.
In the first view (the one from which the segue is coming from) write the following code :
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
// Create a new variable to store the instance of the next view controller
let destinationVC = segue.destinationViewController as CustomViewController
destinationVC.submittedURL = inputURL.text
destinationVC.submittedName = inputName.text
}
Here CustomViewController is the custom class of the UIViewController to which the segue is going to.
To perform the segue programmatically in your button #IBAction do that :
#IBAction func buttonWasClicked(sender: AnyObject) {
performSegueWithIdentifier("submissionSegue", sender: self)
}
Since your view controllers are linked with segue you can override the prepareForSegue method in first view controller and pass data by doing so
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if (segue.identifier == "secondViewController") { // here secondViewController is your segue identifier
var secondViewController = segue.destinationViewController as SecondViewController // where SecondViewController is the name of your second view controller class
secondViewController.submittedURL = inputURL.text
secondViewController.submittedName = inputName.text
}
}
And to performSegue inside your button action use perfromSegueWithIdentifier method
#IBAction func submitUrlButton(sender: AnyObject) {
//replace identifier with your identifier from storyboard
self.performSegueWithIdentifier("secondViewController", sender: self)
}
The simplest way of accessing values globally not neccessary to pass with segue
First View controller
import UIKit
var submittedURL:NSString? // declare them here
var submittedName:NSString? // Now these two variables are accessible globally
class YourViewController : UIViewController
{
#IBOutlet var inputURL: UITextField!
#IBOutlet var inputName: UITextField!
#IBAction func submitUrlButton(sender: AnyObject) {
if inputURL.text == "" && inputName.text == ""
{
//Show an alert here etc
}
else {
self.submittedURL.text = inputURL.text
self.submittedName.text = inputName.text
}
}
}
SecondView Controller
import UIKit
class SecondviewController: UIViewController
{
//inside viewDidload
println(submittedURL)
println(submittedName)
}