The prepare(for segue: ) function runs, but the data is not sent to my destination ViewController. I am getting following error when loading that VC's collection view which has to receive the data:
Unexpectedly found nil while unwrapping an Optional value
I have confirmed that the segue type is a selection segue, the segue identifier is correct, and that the views work as far as displaying dummy data.
First view controller (DrawerVC):
let realm = try! Realm()
var allDrawers: Results<Drawer>?
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
print("goToTool segue")
performSegue(withIdentifier: "goToTool", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToTool" {
print("Prepare for segue from drawerVC ran") // this runs!
let destinationVC = segue.destination as! ToolVC
if let indexPath = tableView.indexPathForSelectedRow {
destinationVC.selectedDrawer = allDrawers?[indexPath.row]
print("Selected drawer set to index path") // doesn't run :(
}
} else if segue.identifier == "goToEditCategory" {
_ = segue.destination as! EditCategoryVC
}
}
Destination view controller (ToolVC):
let realm = try! Realm()
var allTools: Results<Tool>?
var selectedDrawer: Drawer? {
didSet{
// doesn't run since selectedDrawer was never set :(
print("The selected drawer changed from \(oldValue) to \(selectedDrawer?.title)")
loadTools()
}
}
func loadTools() {
allTools = selectedDrawer?.tools.sorted(byKeyPath: "title", ascending: false)
toolCollectionView.reloadData() // this is where I get the optional value error
}
You are making a very common mistake.
In the destination view controller you are accessing the table view in loadTools() which is not connected yet at the moment you assign the selected drawer. Therefore the table view is nil and causes the crash.
A solution is to remove the didSet observer
var selectedDrawer: Drawer?
and load the data in viewDidLoad
func viewDidLoad() {
super.viewDidLoad()
if let drawer = selectedDrawer {
allTools = drawer.tools.sorted(byKeyPath: "title", ascending: false)
toolCollectionView.reloadData()
}
}
And if the segue is connected from the cell to the destination view controller remove the didSelectRowAt method.
Related
I'm trying to pass an object from one view controller to another, but the receiver receives nil and throws an error saying:
Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value: file
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "sPropSegue" {
if let indexPath = tableView.indexPathForSelectedRow {
let prop = modelProperty.props[indexPath.row]
let dVeiwController = segue.destination as? PDViewController
detailVeiwController?.property = prop
}
}
}
code in the UIViewController
var property: Property!
override func viewDidLoad() {
super.viewDidLoad()
propImage.image = UIImage(named: property.imageName)
priceLable.text = property.price
addressTextView.text = property.address //propImage.image = UIImage()
// Do any additional setup after loading the view.
}
please help me solving this problem.
Thank you in advance!
You need to make sure segue is established from the Source vc ( not the table cell ) to the destination vc for override func prepare(for segue to be called
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
performSegue(withIdentifier:"sPropSegue",sender:nil)
}
According to my understanding you are not getting property object in your PDViewController.
So try to debug it. Make sure that prop is not nil.
Try executing the same code after commenting viewDidLoad() code.
Also make sure you have self.table.delegate = self in the controller where you are trying to perform segue.
I'm trying to send data from popup view to DataView.
it actually works ! .However, when I go back to popup view to edit the text it doesn't show the text that was entered and sent to DataView.
I'm sending the data through protocol.
PopupView
protocol DataEnteredDelegate: class {
func userDidEnterInformation(data: String)}
#IBAction func DoneButton(_ sender: Any) {
if let data = openTextView.text {
delegate?.userDidEnterInformation(data: data)
self.dismiss(animated: true, completion: nil)
}
}
DataView
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "openSummary" {
let sendingVC: popupViewController = segue.destination as! popupViewController
sendingVC.delegate = self
}
}
// Protocol receving data from popup
func userDidEnterInformation(data: String) {
addJobSum.text = data
}
After the PopupViewController gets dismissed, it gets destroyed and no new instances are able to know what an old instance had as a text value for the Text View.
To fix it - create a string property inside PopupViewController and initialize the Text View's text property with its value inside some method, such as viewDidLoad():
class PopupViewController: UIViewController {
var textData: String?
/* more code */
func viewDidLoad() {
/* more code */
if let data = textData {
openTextView.text = data
}
}
}
Then, you'll have to inject the proper / needed text for textData inside prepare(for:) method (right before it's presented):
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "openSummary" {
let sendingVC = segue.destination as! PopupViewController
sendingVC.delegate = self
// This is the new line to be added:
sendingVC.textData = addJobSum.text
}
}
I have two ViewControllers in the first I created a tableView where I can insert just a text into a cell.
In the SecondViewController I also have a tableView with the same function, bu HOW can I make it that when I click a cell in the first tableView, I can get into a separate SecondTableView (Array).
So I'm this far, but I think the categorize function must be in the didSelectRowAt, when I click a Row.
FirstViewController:
todos: This is a String Array (I want this as the Category)
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "hhh"{
//let destination = segue.destination as? UINavigationController
let vc = segue.destination as? SecondViewController
}
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let vc = storyboard?.instantiateViewController(withIdentifier: "SecondViewController") as? SecondViewController
//label name
vc?.name = todos[indexPath.row]
self.present(vc!, animated: true, completion: nil)
tableView.deselectRow(at: indexPath, animated: true)
self.performSegue(withIdentifier: "hhh", sender: indexPath)
let indexpath = todos[indexPath.row]
print("indexpath:\(indexpath)")
print("row: \(indexPath.row)")
}
}
In the SecondViewController I have a SecondArray=[String]() these are actually the Todos.
On both ViewControllers I can insert a cell with text but don't know how to pass the data back:=?
In the comments I suggested using a UISplitViewController, as this works well with any kind of master/detail type of app. (In fact, it's an Xcode project type.)
But in case you require using a UINavigationController, here's what I to to "toggle" between two views this way:
FirstViewController:
#IBAction func showFrameVC() {
updateMaskImage()
self.performSegue(withIdentifier: "ShowSecondView", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "ShowSecondView" {
if let vc = segue.destination as? FrameViewController {
vc.someValue = someValue
vc.firstVC = self
}
}
}
Basically, pass the instance of the first view controller along with any data you need to pass.
SecondViewController:
var someValue:String!
weak var subjectVC:FirstViewController!
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if isMovingFromParentViewController {
firstVC.someValue = someValue
}
}
Here you let the navigation controller do it's thing, which is pop the second view controller off the stack after passing back the data it changed. Since you are maintaining a weak value of the first view controller, you free up that memory when the second controller is released.
In your code, you are presenting your SecondViewController in 2 ways in same function.
self.present(vc!, animated: true, completion: nil)
and
self.performSegue(withIdentifier: "hhh", sender: indexPath)
intention of both lines are same, But 2 way of implementation.
if my thinking is right you don't have to perform segue (second line of code mentioned above and also No prepare for segue method).
I want to move from one view controller to another and send userId:
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
self.performSegueWithIdentifier("chosenPerson", sender: self)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "chosenPerson" {
let chosenPerson = segue.destinationViewController as? chosenPersonViewController
let indexPaths = self.collectionView!.indexPathsForSelectedItems()!
let indexPath = indexPaths[0] as NSIndexPath
chosenPerson!.userID = self.usersArray[indexPath.row].userId
}
by clicking I get: "fatal error: unexpectedly found nil while unwrapping an Optional value"
what I do wrong?
If you have given segue in StoryBoard DON'T Call this self.performSegueWithIdentifier("chosenPerson", sender: self) method in didSelectItem
If you have given segue in storyboard override func prepareForSegue - this method calls first after that didSelectItem calls
Please refer storyBoard once (below Image for Sample)
I think problem is in self.usersArray[indexPath.row].userId May this returns nil
Swift2:
self.performSegueWithIdentifier("chosenPerson", sender: self)
Swift3:
self.performSegue(withIdentifier: "chosenPerson", sender: self)
Swift2:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "chosenPerson" {
let chosenPerson = segue.destinationViewController as? chosenPersonViewController
let indexPaths = self.collectionView!.indexPathsForSelectedItems()!
let indexPath = indexPaths[0] as NSIndexPath
chosenPerson!.userID = self.usersArray[indexPath.row].userId //May it found nil please re - check array values
}
Swift3:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "chosenPerson" {
let chosenPerson = segue.destination as! chosenPersonViewController
if let indexPath = collectionView.indexPathForSelectedItem {
chosenPerson!.userID = self.usersArray[indexPath.row].userId //May it found nil please re - check array values
}
}
}
When performing the segue, pass the indexPath as the sender and try using this switch statement. If you see "unknown segue" printed out when you select a cell, the destination controller is not of type chosenPersonViewController.
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
performSegueWithIdentifier("chosenPerson", sender: indexPath)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
switch (segue.destinationViewController, sender) {
case (let controller as chosenPersonViewController, let indexPath as NSIndexPath):
controller.userID = usersArray[indexPath.row].userId
default:
print("unknown segue")
break
}
}
One possible issue could be that in your storyboard you have not set the identifier for your segue to be "chosenPerson". To fix this first make sure you have a segue between your first and second view controllers, which can be created by control dragging one from one view controller to another.
Then make sure the segue has an identifier, specifically: "chosenPerson". To do this: click on the segue between the first two view controllers, then navigate to the attributes tab, and then set the identifier box to be "chosenPerson". Save the storyboard with your changes and now you should be able to call prepareForSegue with that identifier and not experience a fatal error.
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
self.selectedClubState = stateNamesForDisplay[indexPath.row]
self.performSegueWithIdentifier ("Cities", sender: self)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
var clubsToPassToCitiesViewController = [clubObject]()
if segue.identifier == "Cities" {
for club in clubsForTable{
if club.clubState == self.selectedClubState{
clubsToPassToCitiesViewController.append(club)
}
}
let citiesView = segue.destinationViewController as? citiesViewController
citiesView?.clubsForChosenCity = clubsToPassToCitiesViewController
}
}
Segue is being executed twice leading to the next VC. How can I prevent this from happening?
Delete the current segue in storyboard. Then CTRL-drag from the viewController (not the cell) to the next view controller and name it "Cities". Now, when you select a cell, the didSelectRowAtIndexPath() will fire first and will call performSegueWithIdentifier()
However, if all you're looking to do in the didSelectRowAtIndexPath() is get the row that performed the segue, you can maintain your original setup of having the cell segue from the storyboard, remove didSelectRowAtIndexPath() and in prepareForSegue() do:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let indexPath = self.tableView.indexPathForSelectedRow {
self.selectedClubState = stateNamesForDisplay[indexPath.row]
}
var clubsToPassToCitiesViewController = [clubObject]()
if segue.identifier == "Cities" {
for club in clubsForTable{
if club.clubState == self.selectedClubState{
clubsToPassToCitiesViewController.append(club)
}
}
let citiesView = segue.destinationViewController as? citiesViewController
citiesView?.clubsForChosenCity = clubsToPassToCitiesViewController
}
}
You are the one executing the segue twice — once automatically in the storyboard (because your segue emanates as an Action Segue from the cell prototype), and once in code when you say self.performSegueWithIdentifier. If you don't want the segue executed twice, remove one of those.
Personally, my recommendation is that you delete didSelectRow entirely and move your self.selectedClubState assignment into prepareForSegue.