I have a tableview called PostsTableView that has a list of user posts with a UIButton called "Comment". When a user clicks Comment, I would like it to redirect to CommentViewController that has all the information around the post such as the postText and the user who wrote the post.
Snippets of the code below.
PostsTableView
extension PostsTableViewController: PostsTableViewCellDelegate {
func commentTapped(postInfo: String) {
//How do I pass postInfo along to CommentViewController
}
PostsTableViewCell
protocol TableViewCellDelegate {
func commentTapped(postInfo: String)
}
class PostsTableViewCell: UITableViewCell {
#IBOutlet weak var postTextLabel: UILabel!
#IBOutlet weak var postUserLabel: UILabel!
var postItem: Post!
var delegate: TableViewCellDelegate?
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
#IBAction func commentAction(_ sender: Any) {
delegate?.commentTapped(postInfo: postItem.postText)
}
}
Assuming you are using segues, you will call .performSegue(withIdentifier: "mySegueIdentifier", sender: self)
You could store the postInfo first by adding a variable to PostsTableViewController
var selectedPostInfo: String?
And then setting it in commentTapped(postInfo: String)
func commentTapped(postInfo: String) {
selectedPostInfo = postInfo
performSegue(withIdentifier: "mySegueIdentifier")
}
Now override controller.prepare(for: UIStoryboardSegue, sender: Any?) and set the value on CommentViewController:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let controller = segue.destination as? CommentViewController {
controller.postInfo = selectedPostInfo
}
}
You can do something like this
1) Firstof all refactor the delegate method to take post object as an argument instead of just a String (This helps to provide better User Experience since no need to fetch data already available locally at that moment). Something like this
func commentTapped(postObject: Post) { // I am assuming your Post model has got all the info required by the CommentsViewController
}
2) Now create a property in CommentsViewController let's say post, which you can I initialise as below code
func commentTapped(postObject: Post) {
let commentVC = CommentsViewController.initWithNib... // Initialise the Comments ViewController
commentVC.post = postObject // Assign the post object here
show(commentVC) // Present here the commentVC as per your requirement of Modal or Push
}
Related
I'm developing a simple game (my first iOS app!) and am trying to link a variable between two View Controllers. In the first view controller, I have a textfield where the user can type in any number they choose. In the second View Controller, I would like users to be able to generate any number between 1 and the number they entered by pressing a button and be able to keep doing so. However, I am not able to use the "upperBound" variable holding the user-entered value in ViewController2.
I've tried using prepare for segue but it's not working, and I've snooped around stackoverflow and tried a couple of methods without quite knowing what I'm doing to no avail.
(UPDATED) ViewController:
class ViewController: UIViewController, UITextFieldDelegate {
//MARK: Properties
#IBOutlet weak var numberOfPages: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
// Handle the text field’s user input through delegate callbacks.
numberOfPages.delegate = self
}
//MARK: UITextFieldDelegate
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
// Hide the keyboard.
textField.resignFirstResponder()
return true
}
func textFieldDidEndEditing(_ textField: UITextField) {
//Save number entered and then randomly select a number within bounds
}
//MARK: Actions
var upperBound: Int?
#IBAction func setUpperBound(_ sender: UIButton) {
upperBound = Int(numberOfPages.text!)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
// Create a variable that you want to send
var newUpperBound = Int(upperBound!)
// Create a new variable to store the instance of ViewController2
let destinationVC = segue.destination as! ViewController2
destinationVC.upperBound = newUpperBound
}
}
(UPDATED) ViewController2:
class ViewController2: UIViewController, UITextFieldDelegate {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
/*
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Get the new view controller using segue.destination.
// Pass the selected object to the new view controller.
}
*/
//Mark: Actions
#IBAction func roller(_ sender: UIButton) {
//Generate random number
let randomNumber = Int.random(in: 0 ..< upperBound)
}
var upperBound: Int?
}
With this code, I'm getting an error on line 34 of ViewController2 that reads "Use of unresolved identifier upperBound". Additionally, there is an issue on line 40 of ViewController that reads "immutable value upperBound was never used". I would expect to be able to generate a random value between 1 and the entered number so that I can keep working and add more features to my app (like printing these random values etc)
ViewController
import UIKit
class ViewController: UIViewController, UITextFieldDelegate {
#IBOutlet weak var numberOfPages: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
numberOfPages.delegate = self
}
//MARK: UITextFieldDelegate
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
// Hide the keyboard.
textField.resignFirstResponder()
return true
}
func textFieldDidEndEditing(_ textField: UITextField) {
//Save number entered and then randomly select a number within bounds
}
//MARK: Actions
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if numberOfPages.text == ""{
print("Please enter number")
return
}
let upperBound: Int? = Int(numberOfPages.text ?? "0")
if upperBound != 0{
if segue.identifier == "mySegue"{
let vc = segue.destination as! ViewController2
vc.upperBound = upperBound
}
}
}
}
ViewController2
import UIKit
class ViewController2: UIViewController {
#IBOutlet weak var lbl_UpperBound: UILabel!
#IBOutlet weak var btn_Generate: UIButton!
#IBOutlet weak var lbl_Random: UILabel!
var upperBound: Int?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
lbl_UpperBound.text = "Upper Bound - \(upperBound ?? 0)"
btn_Generate.addTarget(self, action: #selector(roller), for: .touchUpInside)
lbl_Random.text = ""
}
#objc func roller(_ sender: UIButton) {
//Generate random number
let randomNumber = Int.random(in: 0 ..< (upperBound ?? 1))
lbl_Random.text = "\(randomNumber)"
}
}
Also Don't forget to name the Segue
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
}
}
}
got 2 ViewControllers 1st is ViewController 2nd TableViewCotnroller
class ViewController: UIViewController, CLLocationManagerDelegate, TabVCDelegate {
func reciveData(_ numberOfRows: Int) {
print(numberOfRows)
}
...
}
TableViewController:
protocol TabVCDelegate {
func reciveData(_ numberOfRows: Int)
}
class TabVC: UITableViewController {
var delegate: TabVCDelegate?
#IBAction func passDataBack(_ sender: UIButton) {
delegate?.reciveData(5)
self.dismiss(animated: true, completion: nil)
print(delegate ?? "show me if its nil")
}
my delegate?.reciveData(5) is for some reason nil can't figure it out
it did worked when i had 2 normal ViewController am i missing something about TableViewControllers? or maybe its something else?
any help would be appreciated.
First of:
Make that delegate property weak to avoid strong reference cycle
weak var delegate: TabVCDelegate?
To achieve that your protocol should conform to class
protocol TabVCDelegate: class {
func reciveData(_ numberOfRows: Int)
}
Next:
You must set that delegate somewhere. If you have reference to TabVC instance in your ViewController class then it would look like this:
tabVC.delegate = self
HERE is detailed description about "how to create delegates in Swift"
thanks
actually i did found what was missing, in segue i forgot to set destinationVC.delegate as self when setting segue
:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToTableView"{
let destinationVC = segue.destination as! TabVC
destinationVC.delegate = self // <-- this line was missing
destinationVC.dataPassedThroughSegue = locationLabel.text
}
}
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.
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.