I have VC "A", from which I pass some data to "B". In attribute inspector i called my seque "B" :
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "B" {
let vc = segue.destination as! ChooseController
vc.someData = "passedDataFromAToB"
}
After that i want to pass some data back from B to A using delegates and protocols, but it turns out that my segue identifier is busy. I have to create new segue? But how, programmatically?
You need to set the delegate here
let vc = segue.destination as! ChooseController
vc.delegate = self
vc.someData = "passedDataFromAToB"
class ChooseController:UIViewController {
weak var delegate:AVC?
then to pass data before dismiss
delegate?.sendData(data)
self.dismiss(animated:true,completion:nil)
Related
I have a storyboard segue that hooks up VC1 to VC2. The identifier is "showDetail", and the destination ViewController class is YTimeCalendarDetailViewController. When I step through the following in my prepareForSegue, it throws a SIGABRT after failing to if let vc = segue.destination as? YTimeCalendarDetailViewController:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == DETAIL_SEGUE_ID,
let vc = segue.destination as? YTimeCalendarDetailViewController,
let selectedDate = selectedDate {
vc.employeeRecord = selectedJob.employeeRecord
vc.punches = timesheet[selectedDate]?.punches ?? []
vc.selectedDate = selectedDate
}
}
I've tripled checked my segue and viewControllers to make sure that they're pointing at the right things, inheriting from the right class etc. When I print out segue.destination in lldb, it tells me that there is a UIViewController, but I don't know how to find the exact class of the VC. Is this an issue with container views? VC2, contains 3 container views that I intend to show/hide via segmented control. But I doubt it...I'm just so out of ideas.
You need to assign the class name to the vc in Ib
let vc = segue.destination as? YTimeCalendarDetailViewController,
it's clear from the print <UIViewController:> , select the vc in IB
For an easy debug always use as! instead of as?
let vc = segue.destination as! YTimeCalendarDetailViewController
I have been following a firebase tutorial to create my own chat application, I am trying to access a chatviewcontroller from the uiviewcontroller containing a table view. The Viewcontroller is embedded in a navigation controller. How can I bring up the chatviewcontroller when a cell is selected?
Here is my code:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
super.prepare(for: segue, sender: sender)
//retrieve the destination view controller
let navVc = segue.destination as! UINavigationController
let channelVc = navVc.viewControllers.chatViewController as! ViewController
// set the senderDisplayName in Viewcontroller to the email provided in the email field by the user
channelVc.senderDisplayName = userEmailTextField?.text
}
Here is the error msg
Assuming your ChatViewController is the root view controller of your navigation controller you should change your code to this:
let channelVc = navVc.viewControllers.first as! ChatViewController
navVC.viewControllers is an array of the UIViewControllers managed by that UINavigationController, so that array would not have a property called chatViewController unless you implemented something custom.
EDIT: To put it all together, and also to demonstrate how to safely unwrap these optionals, your prepareForSegue should look like this:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
super.prepare(for: segue, sender: sender)
if let navVc = segue.destination as? UINavigationController, let channelVc = navVc.viewControllers.first as? ChatViewController {
//Now you have a reference to your ChatVC, and you can set the DisplayName
channelVc.senderDisplayName = userEmailTextField?.text
}
}
You have to get the first view controller from the UINavigationController:
let channelVc = navVc.viewControllers.first as! ChatViewController
I'm new to Swift and to iOS Development. I currently have 2 ViewControllers, a button in the first and a label in the second one. I've connected the first button to the second ViewController and the transition works.
Now, when I try changing the label's text I get the error:
fatal error: unexpectedly found nil while unwrapping an Optional
value
.
Here you find my prepare function in the first ViewController:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "mySegue" {
let vc = segue.destination as! SecondViewController
vc.secondResultLabel.text = "Testing"
}
}
Can it be that the label in the second ViewController is somehow protected ?
Thanks for the help
You need to pass the String to the SecondViewController instead of directing setting it, as the UILabel has not been created yet.
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "mySegue" {
let vc = segue.destination as! SecondViewController
vc.secondResultLabelText = "Testing"
}
}
And in your SecondViewController viewDidLoad method set the UILabel to be the string
var secondResultLabelText : String!
override func viewDidLoad() {
secondResultLabelText.text = secondResultLabelText
}
add a string variable in the second view controller
var labelText: String!
in second view controller also (in viewDidLoad)
self.secondResultLabel.text = self.labelText
then first view controller prepare for segue
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "mySegue" {
let vc = segue.destination as! SecondViewController
vc.labelText = "Testing"
}
}
this is because second view controller's UILabel Outlet is not being initialized yet in prepare for segue
Rikh's answer is the same, both his answer and mine are the same
Welcome aboard :)
Your problem is that your SecondViewController, and more specifically vc.secondResultLabelText is not initiated when you call prepare, so secondResultLabel is actually nil at that time.
You need to add a variable to your SecondViewController like so:
var labelText: String = ""
And then set that value instead:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "mySegue" {
let vc = segue.destination as! SecondViewController
vc.labelText = "Testing"
}
}
In viewWillAppear or viewDidLoad on your SecondViewController you can then use that value for your secondResultLabelText which is now ready, connected, and won't crash
secondResultLabelText.text = labelText
Hope that helps.
First take a global variable in SecondViewController... eg I took "secondViewControllerVariable". Then get the text you want to display in your SecondViewController.
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if segue.identifier == "mySegue"
{
let vc = segue.destination as! SecondViewController
vc.secondViewControllerVariable = "Your string you get in FirstViewController"
}
}
And then in your SecondViewController, in viewDidLoad method set the UILabel to be the string
var secondViewControllerVariable : String! // You have to declare this first in your SecondViewController Globally
override func viewDidLoad()
{
vc.secondResultLabelText.text = secondViewControllerVariable
}
That's it. Happy Coding.
I'm learning Swift and I am working through passing items from one segue to another. From what it seems to me in the code, you are creating a new ViewController object called "secondVC". In line 3, it seems to me like it's duplicating the segue.destinationViewController by setting this new controller equal to the segue.destinationViewController. In other words, I don't understand how secondVC is actually a reference to this second view controller, instead of being a duplicated instance. Where is my fault in thinking? Here is the code:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
var secondVC:SecondViewController = SecondViewController()
secondVC = segue.destinationViewController as SecondViewController
secondVC.delegate = self
}
Thank you very much!
I'm learning swift too - From my own experience, you use prepareForSegue to pass in data to the secondVC right before the segue starts.
Here's some sample code. I use prepareForSegue to pass in task data into the second view controller. There are other ways to do this, this is just one way.
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showTaskDetail" {
let detailVC: TaskDetailViewController = segue.destinationViewController as TaskDetailViewController
let indexPath = self.tableView.indexPathForSelectedRow()
let thisTask = fetchedResultsController.objectAtIndexPath(indexPath!) as TaskModel
detailVC.detailTaskModel = thisTask
detailVC.delegate = self
}
I am developing an iOS application in Swift.
I want to send data from a view to an other one, using the prepareForSegue function.
However, my target view is preceded by a navigation controller, so it doesn't work. How can I set data on the VC contained within the navigation controller?
In prepareForSegue access the target navigation controller, and then its top:
let destinationNavigationController = segue.destination as! UINavigationController
let targetController = destinationNavigationController.topViewController
From the target controller you can access its view and pass data.
In old - now obsolete - versions of Swift and UIKit the code was slightly different:
let destinationNavigationController = segue.destinationViewController as UINavigationController
let targetController = destinationNavigationController.topViewController
Prepare the segue in the SendViewController
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "segueShowNavigation" {
if let destVC = segue.destination as? UINavigationController,
let targetController = destVC.topViewController as? ReceiveViewController {
targetController.data = "hello from ReceiveVC !"
}
}
}
Edit the identifier segue to "showNavigationController"
In your ReceiveViewController add
this
var data : String = ""
override func viewDidLoad() {
super.viewDidLoad()
print("data from ReceiveViewController is \(data)")
}
Of course you can send any other type of data (int, Bool, JSON ...)
Complete answer using optional binding and Swift 3 & 4:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let navigationVC = segue.destination as? UINavigationController, let myViewController = navigationVC.topViewController as? MyViewControllerClass {
myViewController.yourProperty = myProperty
}
}
Here is the answer for Swift 3:
let svc = segue.destination as? UINavigationController
let controller: MyController = svc?.topViewController as! MyController
controller.myProperty = "Hi there"
A one liner in Swift 3:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let vc = segue.destination.childViewControllers[0] as? FooController {
vc.variable = localvariable
}
}
In Swift 5
If you must not only segue from a SourceViewController to a DestinationViewController embedded in a UINavigationController, but also to a new Storyboard also, then do the following...
Place a "Storyboard Reference" object from your Object Library next to your source ViewController in Interface Builder, and then drag a segue to it (from a button on the SourceViewController view, for instance). Name the segue identifier "ToOtherStoryboard", for example.
Go to NavigationViewController and give it a Storyboard ID using the Identity Inspector. "DestinationNavVC" would do.
Click the Storyboard Reference icon you created in step 1, and in its attribute inspector's 'Referenced ID' field, enter the Storyboard ID you wrote for the UINavigationController in step 2. This creates the segue from source to the DestinationViewController no matter what you write in source file of the source ViewController. This is because seguing to a NaviationController will automatically show the root ViewController (the first one) of the UINavigationController.
(OPTIONAL) If you need to attach data along with your segue and send it to properties within the DestinationViewController, you would write the following code inside a Prepare-For-Segue method in your SourceViewController file:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "ToOtherStoryboard" {
let destinationNavVC = segue.destination as! UINavigationController
let destinationVC = destinationNavVC.topController as! DestinationViewController
destinationVC.name = nameTextField.text // for example
destinationVC.occupation = occupationTextField.text
}
}
You do not NEED to have a PrepareForSegue if you're simply trying to move from one ViewController to another, the methods above will work (w/o step 3)
In your IBAction Outlet method for your button you used to initiate the segue, you would write:
performSegue(withIdentifer: "ToOtherStoryboard", sender: self)
Set the identifier name in the segue arrow property in order to use in the the performeSegue.
Like this:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let vc: ProfileViewController = segue.destination as? ProfileViewController {
//do any setting to the next screen
}
}
and then:
performSegue(withIdentifier: "yourIdentifierOfViewProfile", sender: indexPath.row)
I hope it helps.
It's a good idea to skip the check for UINavigationController as there may be multiple segues that use a navigationController and so will go into that check for every segue that uses a navigationController. A better way is to check the first viewController of the children and cast it as the viewController you are looking for.
if let destVC = segue.destination.children.first as? MyViewController {
destVC.hideBottomBar = true
}