I just going crazy on Swift Popover “return” values. I am new to Objectiv-C as well as SWIFT but I try to focus on SWIFT.
I checked out tutorials around Google and StackOverflow about how to manage iOS popovers, learned a lot but the last peace I couldn’t make it. It is great so see how easy it is made using Swift and Xcode 6, love it, but I could not figure out how to get back the selected value from my popover to my calling view controller.
So here is my problem:
(SIDENOTE: I am using SWIFT and do all using storyboard)
I have created a master ViewController with a button to select currencies. This button opens a “select currency” popover (linked to the CurrencyTableViewController (CTV) by CTRL-Dragging it to the CTV-Controller.
So far so good. The thing is, I have no idea how to get back the selected table row (currency) from the CTV-Table ;-( So I need the selected currency (table row) in the calling ViewController.
This is an excerpt from my ViewController (which is calling the popover)
class ViewController: UIViewController, UIPopoverPresentationControllerDelegate
[...]
// This button is calling the popover
#IBAction func buttonCurrency(sender: AnyObject) {
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let controller = segue.destinationViewController as? CurrencyTableViewController {
controller.popoverPresentationController?.delegate = self
return
}
}
[...]
Hopefully somebody can help me with that missing last mile how to get back the selected row value back to my ViewController.
Thanks in advance
Cheers
John
I made quick example, hope it helps:
// This is you popover's class
#objc protocol CurrencySelectedDelegate {
func currencySelected(currName: String)
}
class MyPopOverController: UIViewController {
weak var delegate: CurrencySelectedDelegate?
#IBAction func readyButtonPressed(sender: AnyObject) {
// Do what you want
delegate?.currencySelected("Euro/Dollar etc....")
// close popover
}
}
// ViewController
class ViewController: UIViewController, CurrencySelectedDelegate {
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "mySegue" { // your identifier here
let controller = segue.destinationViewController as! MyPopOverController
controller.delegate = self
}
}
}
And remember just declare that currencySelected function in your ViewController.
Related
my problem looks so simple, but since I am a beginner, I have problem to understand the concept of the closure to pass data between two controllers
for example I have a static table view controllers that has one cell and a title inside it
class FirstView: UITableViewController {
#IBOutlet weak var titleLabel: UILabel!
and I have an another view controller that contain a button inside it
class SecondViewController: UIViewController {
#IBAction func pressChangeButton(_ sender: UIButton) {
}
and there is segue1 between these two controllers, with identifier "segue1"
I want a to a simple task, I want to add a boolean closure that it will be true if the change button is pressed.
that is why I create a closure function the second view controller that has change button.
var change : ((Bool) -> Void)?
I just want, that the second view controllers tells the first one that change closure is now true (after pressing the change button) and the first view controllers simply change the title table inside it to whatever (I just want to see that how it can be done)
I don't know I have to use prepare sugue function?
Could anyone help me to understand this concept?
You can try
class FirstView: UITableViewController {
#IBOutlet weak var titleLabel: UILabel!
#IBAction func goToSecond(_ sender: UIButton) {
self.performSegue(withIdentifier: "segue1", sender: nil)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "segue1" {
let des = segue.destination as! SecondViewController
des.change = { [weak self] (value) in
print(value)
self?.titleLabel.text = "SetValue"// set a value
}
}
}
}
class SecondViewController: UIViewController {
var change : ((Bool) -> Void)?
#IBAction func pressChangeButton(_ sender: UIButton) {
change?(true)
}
}
A closure is basically a piece of code that you can run. In Swift a closure is a first class citizen as it can be passed around as parameters and return type of functions. That being said, you can pass or set a closure as you normally would for other objects.
As per Sh_Kan's answer, just set SecondViewController's closure in prepare(for segue:sender:), always paying extra attention to retain cycles. You might also want to take a look at delegate design pattern in order to exchange data and messages between your controllers.
Since i'm new and a newbie on Swift can someone tell me how I can get the label value on screen 1 to show on screen 2. Thanks
Edit: So I tried the way you told me but for some reason the Label text did not change in View 2. Any help? Thanks
I am passing textFiled data to destViewController to show how segue performs when passing data.
Note: If you want to pass string data to your destVC.You can assign your string like var someValue: String
mainStoryBoard:
MainVC:
#IBOutlet weak var textField: UITextField!
//or you can assign string like var someValue: : String
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let viewController = segue.destination as! destVC
viewController.dataText = textField.text // someValue.text
}
DestVC:
#IBOutlet var label: UILabel!
var dataText = String()
override func viewDidLoad()
label.text = dataText
}
Output:
You already have a segue between ViewController1 and ViewController2 it seems, so now you just need to pass some date from one to another. This can be done in the function prepare(for segue: UIStoryboardSegue, sender: AnyObject?) which is called when you transition from ViewController1 to ViewController2.
The UIStoryboardSegue class has a property called source of type UIViewController and another property called destination which is also a UIViewController.
So, if you define a property on your ViewController2, like so:
var labelValue: String
Then you can pass a value to it in your prepareForSegue defined on ViewController1 like so:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard let viewController2 = segue.destination as? YourViewController2 else {
return
}
viewController2.labelValue = theValueFromViewController1
}
Here is tutorial telling you a bit more (in Objective C though)
And this is also a fine introduction.
Hope that helps you.
I'll consider you have ViewController class VC1 (screen 1) & ViewController class VC2 (screen 2). I see from the screenshot that, you're already using a segue to go from the VC1 to VC2 view.
Now, declare a variable in your VC2 class let's call it labelValue,
class VC2 {
var labelValue: String?
...
}
Whenever you use a storyboard segue to move from one viewcontroller's view to other viewcontroller's view a method named,
func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?)
will get called if it's overriden in the source viewController class (scene1 in your case). In this method you'd be able to access the destination view controller (scene 2) and it's properties. So for your case you can implement it like this,
class VC1 {
//I have assumed the below label will hold the value which you want to pass it to the scene 2.
var lblResult: UILabel!
......
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// You can access the VC2 instance from the segue
if let vc2 = segue.destinationViewController as? VC2 {
vc2.labelValue = lblResult.text
}
}
Now once you implement the prepareForSegue: method correctly as shown above, you'd be able to get the label's value from scene 1 to labelValue property of scene2.
Do learn more about segues here : More About Segues and Storyboards here.
================================
Edit:
Coming to your edited question, in your View2 viewController, you've declared labelNumber1 as String and not as UILabel, so whenever you pass the value to labelNumber1, the value will be containing in this variable and it will not be shown in the screen since it is just a normal string. So what you can do is, declare the labelNumber1 as UILabel
class View2: UIViewController {
#IBOutlet var labelNumber1: UILabel!
.....
}
and in your prepare for segue in ViewController1 make the following change,
class ViewController1: UIViewController {
.....
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// You can access the VC2 instance from the segue
if let view2 = segue.destinationViewController as? VC2 {
view2.labelNumber1.text = lblResult.text
}
}
However if you still want to keep labelNumber1 as String, and to verify whether the value has been passed from ViewController1 during segue, add below line to viewDidLoad() of View2 ViewController.
class View2: UIViewController {
.....
override func viewDidLoad() {
super.viewDidLoad()
print("labelNumber1: \(labelNumber1)")
}
}
And you can see the printed value of labelNumber1 in the console.
HTH :)
I have been learning swift and have made the foundation of most of my app. I have the following storyboard
app storyboard
Everything works fine. For example, I have an unwind segue on the add course view controller that triggers when you press save and you are returned to the 'your courses' view controller.
When you are on the my courses view controller, you can select a course and the topics are displayed, you can then select a topic and you are taken to an update score view controller, this all works fine.
However, my problem is this. I want to make it so that when you select save in the updatescore view controller, an unwind segue is triggered (the same as in the add course) and you are returned to the list of topics in the topics view controller.
However, I have followed many tutorials and obviously got it working before. (My action method for the unwind segue is in the correct topics view controller) but when i press save, the unwind segue is not returning me to the topics view controller.
Could anyone suggest a reason for this? I have spent a lot of time trying to find an answer and gone through many tutorials but have not managed to solve it.
I have also included a screen shot of the connections of the triggered segues for my save button to show that it is set up. Showing triggered segue for save button
i have the following code in the update score view controller
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if saveButton === sender {
print("save button selected")
}
}
But even this is not getting triggered when I click on save.
Many thanks
UPDATE:
After following Ronatorys advice My view controller for the update score is as follows but it is still not working:
import UIKit
class UpdateScoreTableViewController: UITableViewController {
#IBOutlet weak var topicGettingUpdated: UITextField!
#IBOutlet weak var newScore: UITextField!
#IBOutlet weak var saveButton: UIBarButtonItem!
var index:Int?
var Topics:[String]!
var TopicToUpdate:String?
override func viewDidLoad() {
super.viewDidLoad()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
guard let uiBarButtonItem = sender as? UIBarButtonItem else {
print("There is no UIBarButtonItem sender")
return
}
}
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
if indexPath.section == 0 && indexPath.row == 0 {
newScore.becomeFirstResponder()
}
tableView.deselectRowAtIndexPath(indexPath, animated: true)
}
}
But the prepare for segue is not even getting triggered.
Like Craig in the comments said, it's not that easy to find the problem. So I just build a simple app where you can follow the steps as guide and see if you forgot something to setup the functionality right. Hope it will help you. Note: Code is in Swift 3.0, but should be easy to adopt to 2.*
1. Storyboard with two View Controllers:
2. Declare the action method for the unwind segue in the FirstViewController.swift:
class FirstViewController: UIViewController {
// action method for the unwind segue
#IBAction func updateScore(_ segue: UIStoryboardSegue) {
print("Back in the FirstViewController")
}
}
3. Connect the Save button in the Storyboard with the action method (with ctrl + drag):
4. Connect your Save button with the SecondViewController.swift file, to use it for checking in your prepareSegue method (with ctrl + drag):
5. Add the prepare(for:sender:) method to your SecondViewController.swift:
class SecondViewController: UIViewController {
#IBOutlet weak var saveButtonPressed: UIBarButtonItem!
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// check safely with guard that your save button is the sender and you can use it
// if not print message
guard let uiBarButtonItem = sender as? UIBarButtonItem else {
print("There is no UIBarButtonItem sender")
return
}
// check if you selected the save button
if saveButtonPressed == uiBarButtonItem {
print("save button selected")
}
}
}
Result:
The sample app you can find here
I did not manage to get the unwind segue to work but instead used
navigationController!.popViewControllerAnimated(true)
as a work around and this works fine.
I have spent a full day now building and re-building a simple popover view. But no matter what I do the popover view extends all the way down to the bottom of the ViewController the popover is displayed in. I'm a newbie but have googled this the whole day and can't find any solutions that works for me. I will appreciate any help! Find my code below:
ViewController:
class ViewController: UIViewController,
UIPopoverPresentationControllerDelegate {
...
#IBAction func studyButtonPressed(sender: AnyObject) {
self.performSegueWithIdentifier("StudyPopover", sender: self)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "StudyPopover" {
let vc = segue.destinationViewController
let controller = vc.popoverPresentationController
if controller != nil {
controller?.delegate = self
}
}
}
func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
return .None
}
Here is a screenshot of the result. The popover is supposed to be 50 by 50, but it extends right down to the bottom of the ViewController.
So I have finally been able to find a solution for this issue. I had a breakthrough when I realised that the popover worked fine when on most device simulations but didn't work for iPhone 6 plus. Then I could narrow down my search for solutions and finally found that I had to add traitCollection: UITraitCollection to my adaptivePresentationStyleForPresentationController function.
func adaptivePresentationStyleForPresentationController(controller: UIPresentationController, traitCollection: UITraitCollection) -> UIModalPresentationStyle {
return .None
}
This makes the popover behave the same way either it's on a normal sized iPhone, iPhone 6 plus or iPad device.
when I am selected button twice will open a new page.
//////
Main viewController
var Country = []
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
#IBAction func taxiAction(sender: AnyObject) {
let opt = ["1","2","3","4","5"]
Country = opt
performSegueWithIdentifier("viewPlaceSegu", sender: sender)
}
...
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// get a reference to the second view controller
if segue.identifier == "viewPlaceSegu" {
if let secondViewController = segue.destinationViewController as? TableViewPlace {
// set a variable in the second view controller with the String to pass
secondViewController.tnt = Country as! [String]
}
}
}
////
http://i.stack.imgur.com/LKrN7.jpg
I tried so but didn't realize problem .
Does anyone know about this? :)
A likely cause is that you have connected the segue from the button to the new ViewController in the storyboard. When the button is pressed it will load the segue created in storyboard as well as the one created programatically.
If this is the cause then you would just need to delete the storyboard segue and create a new one from the ViewController rather than from the button.