i'm trying to create a view controller programmatically that will be opened if a cell on a table is clicked. i'm using a table view and i'm filling it with a xib.So, i'm stuck at the point of referencing the new view controller from the first one on click on a cell created in the table view via xib.
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let vc = storyboard?.instantiateViewController(withIdentifier: "DViewController") as? DViewController
self.navigationController?.present(vc!, animated: true, completion: nil) //present della view successiva
vc?.name = data[indexPath.row].nome
}
this code allows me to click on the row but when clicked it shows an error "Fatal error: Unexpectedly found nil while unwrapping an Optional value" generated apparently from the self.navigationController?.present(vc!...the vc value result to be nil and i can't figure out why.
THis is the ViewController that i want to open on click and the only thing that it has to do is open and change the tile to the name ow the cell that i've clicked onto in the other ViewController
class DViewController: UITableViewController {
var name = ""
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.navigationBar.topItem?.title = "\(name)"
}
}
Can someone help?i'm new to swift...ty
Based on what you mentioned. You can initialize your viewController without stroyboard, and there is no crash anymore.
let vc = DViewController()
If you present your view controller like what you did, it won’t display the title you wish.
To display the title, there are 2 ways you can do:
Display your new view controller with Pushing style:
let vc = DViewController()
navigationController?.pushViewController(vc, animated: true)
Keep using presenting style, but you need to wrap your view controller in other navigation controller:
let vc = DViewController()
let nav = UINavigationController(rootViewController: vc)
navigationController?.present(nav, animated: true)
Related
I have controller1 -> TableViewController2 -> TableViewController3 in my storyboard. When I press a button in controller1, I want to jump to TableViewController3 and from there when I select a row, I want to go back to TableViewController2 and get some data and then go back to controller1.
In controller1 instantiate TableViewController3:
if segue.identifier == "MySegue" {
let viewController:TableViewController3 = segue.destination as! TableViewController3
viewController.addLocationToMap = true
}
In TableViewController3 instantiate TableViewController2 like this:
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
if addLocationToMap == true {
let navc:UINavigationController = self.navigationController!
let tvc:UITableViewController = TableViewController2()
let rootView = navc.viewControllers[0]
navc.setViewControllers([rootView, tvc], animated: true)
return
}
In TableViewController2 viewDidLoad, it fails in ViewDidLoad when I try to set a text field value because the textfield is nil. It cannot be because Textfield is already in the view. Looks like the TableViewController2 view never got loaded.
in TableViewController2
override func viewDidLoad() {
super.viewDidLoad()
locationPurposeTextField.text = "sometext"
}
Fails when setting text value because locationPurposeTextField is nil.
How to fix this?
EDITS:
On pressing a button In controller1:
let navc:UINavigationController = self.navigationController!
let alTvc = self.storyboard!.instantiateViewController(withIdentifier: "AddLocationID") as! UITableViewController
navc.pushViewController(alTvc, animated: false)
let cListTvc = self.storyboard!.instantiateViewController(withIdentifier: "ContactListID") as! UITableViewController
navc.pushViewController(cListTvc, animated: true)
The code takes me to TableViewController3 with storyboard ID: ContactListID as desired.
Next, in TableViewController3
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
self.myDelegate?.userSelectedContact(contactIdentifier: self.contactId, contactFullName: fullName, contactSelected: true)
let navc:UINavigationController = self.navigationController!
let tvc:UITableViewController = self.storyboard!.instantiateViewController(withIdentifier: "AddLocationID") as! UITableViewController
let rootView = navc.viewControllers[0]
navc.setViewControllers([rootView, tvc], animated: true)
}
Takes me to TableViewController2 with storyboard ID: AddLocationID
Based on the delegate sent TableViewController3, in ViewDidappear method of TableViewController2, I set some text in the view and call tableview.realoadData(). It does not load the view.
However if I select a button in TableViewController2 and load TableViewController3 and then comeback to TableViewController2 upon execution of the very same method didSelectRow it reloads the view in TableViewController2
How to fix it, please let me know?
There are a couple of things wrong with your approach.
If you want to go from controller1 to TableViewController3 but have your navigation stack contain controller1 -> TableViewController2 -> TableViewController3, you will have to have the button in controller1 first push TableViewController2 without animation, and then push TableViewController3 with animation. (You won't be able to have your button trigger a segue.)
Second problem: You can't create a copy of your TableViewController2 by just invoking it's initializer (TableViewController2()). When you do that it doesn't load its views from the storyboard. Instead, you should assign a storyboard identifier to it and use the UIStoryboard method instantiateViewController(withIdentifier:) to create a new instance of it.
I have two viewControllers in my App, the code for the first viewController is as illustrated below:
import UIKit
class firstViewController: UIViewController {
// The below two variables will be passed from the firstViewController to the secondViewController then back again from the secondViewController to the firstViewController:
var selectedRowValue: Int = 0
var selectedSectionValue: Int = 0
let main = UIStoryboard(name: "Main", bundle: nil)
lazy var secondViewController = main.instantiateViewController(withIdentifier: "secondViewController")
override func viewDidLoad() {
super.viewDidLoad()
}
// The below function will be triggered when the user tap on a specific tableView cell detailClosure icon. This is when the needed data get sent from this viewController to the secondViewController:
func tableView(_ tableView: UITableView, accessoryButtonTappedForRowWith indexPath: IndexPath) {
let secondViewControllerProperties = secondViewController as! secondViewController
secondViewControllerProperties.receivedSelectedSectionValueFromFirstVc = indexPath.section
secondViewControllerProperties.receivedSelectedRowValueFromFirstVc = indexPath.row
// The below is the relevant content of a UILabel inside the tapped tableView cell by the user that get send to the secondViewController for it to be displayed as its NavigationBar title:
secondViewControllerProperties.selectedUniversalBeamSectionDesignation = arrayWithAllDataRelatedToUbsSections.filter({ $0.sectionSerialNumber == "\(arrayWithAllSectionsSerialNumbers[indexPath.section])" }).map({ $0.fullSectionDesignation })[indexPath.row]
self.present(secondViewControllerProperties, animated: true, completion: nil)
}
}
// The below extension inside the firstViewController is used to pass data back from the secondViewController to the firstViewController:
extension firstViewController: ProtocolToPassDataBackwardsFromSecondVcToFirstVc {
func dataToBePassedUsingProtocol(passedSelectedTableSectionNumberFromPreviousVc: Int, passedSelectedTableRowNumberFromPreviousVc: Int) {
self.selectedRowValue = passedSelectedTableRowNumberFromPreviousVc
self. selectedSectionValue = passedSelectedTableSectionNumberFromPreviousVc
}
}
Below is the code inside the second view controller:
import UIKit
class secondViewController: UIViewController {
weak var delegate: ProtocolToPassDataBackwardsFromSecondVcToFirstVc?
// The below variables get their values when the data get passed from the firstViewController to the secondViewController:
var receivedSelectedRowValueFromFirstVc: Int = 0
var receivedSelectedSectionValueFromFirstVc: Int = 0
var selectedUniversalBeamSectionDesignation: String = ""
// Inside the below navigationBar declaration, its labelTitleText will depend on the tapped tableViewCell by the user inside the firstViewController:
lazy var navigationBar = CustomUINavigationBar(navBarLeftButtonTarget: self, navBarLeftButtonSelector: #selector(navigationBarLeftButtonPressed(sender:)), labelTitleText: "UB \(selectedUniversalBeamSectionDesignation)", navBarDelegate: self)
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(navigationBar)
}
// The below gets triggered when the user hit the back button inside the navigationBar of the secondViewController. This is where using the Protocol data get passed back to the firstViewController:
extension secondViewController: UINavigationBarDelegate {
#objc func navigationBarLeftButtonPressed(sender : UIButton) {
if delegate != nil {
delegate?.dataToBePassedUsingProtocol(passedSelectedTableSectionNumberFromPreviousVc: self.selectedTableSectionNumberFromPreviousViewController, passedSelectedTableRowNumberFromPreviousVc: self.selectedTableRowNumberFromPreviousViewController)
}
dismiss(animated: true) {}
}
}
However, what I am noticing is whenever the secondViewController gets dismissed when the user hit on the back button inside the navigationBar of the secondViewController. The secondViewController does not get de-initialized, and therefore, whenever I press on a different cell inside the tableView inside the firstViewController, the navigationBar title that gets displayed inside the secondViewController is still the same as the one displayed when I pressed the first time. Since the secondViewController did not get de-initialzied and thus, I am seeing the same values as the first time it got initialized.
My question is how to de-initialize the secondViewController when it gets dismissed, so that every time I tap on a different cell inside the tableView inside the firstViewController a new secondViewController gets initialized?
Your code generates secondViewController once and reuses it (it's a property).
lazy var secondViewController = main.instantiateViewController(withIdentifier: "secondViewController")
It means it will live until the first view controller is destroyed, and of course - will be reused.
Instead, you should create it as needed.
func tableView(_ tableView: UITableView, accessoryButtonTappedForRowWith indexPath: IndexPath) {
// Create the second view controller
let secondViewController = main.instantiateViewController(withIdentifier: "secondViewController")
let secondViewControllerProperties = secondViewController as! secondViewController
secondViewControllerProperties.receivedSelectedSectionValueFromFirstVc = indexPath.section
secondViewControllerProperties.receivedSelectedRowValueFromFirstVc = indexPath.row
// The below is the relevant content of a UILabel inside the tapped tableView cell by the user that get send to the secondViewController for it to be displayed as its NavigationBar title:
secondViewControllerProperties.selectedUniversalBeamSectionDesignation = arrayWithAllDataRelatedToUbsSections.filter({ $0.sectionSerialNumber == "\(arrayWithAllSectionsSerialNumbers[indexPath.section])" }).map({ $0.fullSectionDesignation })[indexPath.row]
self.present(secondViewControllerProperties, animated: true, completion: nil)
}
}
Remove the lazy var of course, it is no longer needed.
Also, you could just do:
let secondViewController = main.instantiateViewController(withIdentifier: "secondViewController") as! SecondViewController instead of casting it later, it's a bit cleaner.
I am trying to present a message viewController after pressing a button that is inside of a UiView. When I press the button, the message viewController presents itself, but it is missing some data. I have a separate viewController that allows me to push the controller. I will leave pictures below to show what I am talking about.
This is what the message view controller is supposed to look like, and this what the code looks like to get there
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
dismiss(animated: true) {
print("Dismiss completed")
let user = self.user[indexPath.row]
self.messagesController?.showChatControllerForUser(user)
}
}
This is what happens when I push the view from the UiView, and this is what the code looks like to get there.
#objc func handleNewMessage() {
let chatLogController = ChatLogController(collectionViewLayout: UICollectionViewFlowLayout())
chatLogController.user = user
let navVC = UINavigationController(rootViewController:chatLogController)
self.window?.rootViewController?.present(navVC, animated: true, completion: nil)
}
All of the data pushes through, but the back button is missing, and I am not allowed to actually send a message. I am using two different methods to get to the same controller and I am expecting to see the same result. I was wondering if someone possibly new how to fix this issue?
Back button is not displaying because you are presenting the chatLogController using below function.
#objc func handleNewMessage() {
let chatLogController = ChatLogController(collectionViewLayout: UICollectionViewFlowLayout())
chatLogController.user = user
let navVC = UINavigationController(rootViewController:chatLogController)
self.window?.rootViewController?.present(navVC, animated: true, completion: nil)
}
if you are push to chatLogController from messagesController then you are display a back button on chatLogController.
Note: back button is automatically display when you push to another viewController, it is not display when you present the viewController.
I'm new to swift and I'm trying to learn how to pass data between view controllers and use firebase along with it. This is my segue to a new controller with it setting a variable on that view controller I'm pushing to.
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let viewController = storyboard?.instantiateViewController(withIdentifier: "UserInfoViewController") as! UserInfoViewController
viewController.uidPassed = userUIDArray[indexPath.row]
self.present(viewController, animated: true, completion: nil)
}
It segues to the new controller where I have the variable declared as a string. When I go to run this it crashes with it saying that the string was empty. I can print it and it is empty in the viewDidAppear method, but the viewDidLoad method it has the UID stored in the variable from when I clicked on in the previous controller. Am I not passing the variable from one view controller to the other correctly?
override func viewDidAppear(_ animated: Bool) {
databaseRef.child("Users").child(self.uidPassed).child("Name").observe(.value, with: { (snapshot) in
let name = snapshot.value as! String
print(name)
})
There are two main ways to pass data from one view controller to another view controller.
First, you can connect your cell with the destination view controller in storyboard. In this case you will define the type of segue in storyboard, and you need to define an identifier for the segue in storyboard. When you want to pass data, you need to do it in prepareForSegue method, like this
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destinationViewController = segue.destination as? YourTableViewController {
destinationViewController.texts = self.texts
//...
}
}
Second, you can do this programmatically, like what you are trying to do in your example. In this case you should not connect view controllers by segue in storyboard. Instead, you set an identifier for the destination view controller itself. Then you initiate that controller in the code, set properties to the initiated view controller object and then present it, like what you are doing in your example.
Hope that helps.
This sounds like a typing issue. It seems like userUIDArray holds an array of UID's (not sure what type this is), and you're trying to assign it to viewController.uidPassed, which sounds like it's expecting a string. Try this:
viewController.uidPassed = userUIDArray[indexPath.row] as! String
The other option is to change the type of uidPassed to whatever type of value the userUIDArray variable holds.
Scenario: Master(TableView) --> Detail.
Modus Operandi: Select Row --> display DetailVC
As you can see below, I have a MasterVC embedded in a UINavigationController:
I currently display the DetailVC via pushing it into the UINavigationController's VC stack:
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
println("tableView didSelectRowAtIndexPath")
let storyboard = UIStoryboard(name: "Bliss", bundle: nil);
let controller = storyboard.instantiateViewControllerWithIdentifier("DiaryPlayerVC") as DiaryPlayerViewController
self.navigationController?.pushViewController(controller, animated: true)
}
This works fine.
However, the 'prepareForSeque' doesn't fire:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showDiaryPlayer" {
if let indexPath = self.tableView.indexPathForSelectedRow() {
let object = objects[indexPath.row] as NSDate
// (segue.destinationViewController as DiaryPlayerViewController).detailItem = object
}
}
}
I understand that I probably have two (2) conflicting paradigms here:
1) Using the UINavigationController vs
2) Using the Storyboard Relationship.
So...
Option 1: it appears that I can remove the Segue link to have a storyboard stand-alone DetailVC.
Option 2: via Segue, I'm assuming I can remove the UINavigatorController from the link.
I'm currently using Option #1, launching the DetailVC via the UINavigationController.
Question: If I choose Option #2, how do I access (launch) the DetailVC ("Diary Player") from the Master's Row and hence, fire the Segue's 'prepareForSegue()'?
Answer: create a segue from the table view cell to the detail view controller.
Your screenshot shows that you already created a segue in your storyboard. Give that segue an identifier in its property inspectory. Then you can simply perform the segue in the didSelectRowAtIndexPath method:
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
println("tableView didSelectRowAtIndexPath")
performSegueWithIdentifier("mySegueIdentifier", sender: nil)
}
Note: Ctrl-drag the segue from the TableViewController icon, not from the TableViewCell.