I have one view controller with a button that when clicked goes to a second view controller with a table view. The two scenes are linked through storyboard, as Present Modally. I want the text of the button in the first view controller to change when a row is selected in the table view of the second view controller.
Is there a reason why the button is not changing when the cell is selected?
Any help would be greatly appreciated, I'm still a beginner with Swift.
Below are the relevant lines of code:
View Controller 1
class ChartsViewController: UIViewController {
#IBOutlet weak var titleButton: UIButton!
}
extension ChartsViewController: ModalDelegate {
func didSelectValue(value: String) {
self.titleButton.setTitle(value, for: .normal)
}
}
View Controller 2
protocol ModalDelegate: class {
func didSelectValue(value: String)
}
class DashboardModalViewController: UIViewController {
var delegate: ModalDelegate?
}
extension DashboardModalViewController: UITableViewDelegate {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let rowTitle = self.rows[indexPath.row].text
print (rowTitle)
delegate?.didSelectValue(value: rowTitle)
dismiss(animated: true, completion: nil)
}
}
I think you need to set the second controller's delegate in View Controller 1's prepare method for segue like:
// 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?) {
if let dashboardModalViewController = segue.destination as? DashboardModalViewController {
dashboardModalViewController.delegate = self
}
}
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I know this question has been asked so many many times. But here the scenario is changed. I am using MMParallaxView and that looks pretty awesome.
But Now at this point, I want to communicate between these two View controllers. Let me tell you that this github code helps us to make a view like ios Map App. I mean you can have Map (as 1st view controller) and you can have a list of places view controller on top of 1st View Controller. Just same like Map app.
Now I want to click on the UITableView cell and want to navigate on map. For this I know how to catch delegated method. And I am successfully getting of taps on the UItableView cell. But How to send that clicked item data to 1stView Controller so that It can show or mark selected area on Map.
I know this can also be done. But how?
To modify the example app for MMParallaxView...
In ChildBottomViewController.swift
Add this at the top (outside of the class):
protocol CellTapDelegate {
func didSelectRow(indexPath: IndexPath)
}
Add this line at the beginning of the class:
var cellTapDelegate: CellTapDelegate?
Change didSelectRowAt function to:
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
DispatchQueue.main.async { [weak self] in
self?.cellTapDelegate?.didSelectRow(indexPath: indexPath)
}
}
In MapViewController.swift
Change the class declaration to:
class MapViewController: UIViewController, CellTapDelegate {
and add this function:
#objc func didSelectRow(indexPath: IndexPath) {
print("Delegate got didSelectRow for: \(indexPath)")
}
Then, in SecondViewController.swift
Add this at the end of viewDidLoad():
var mapVC: MapViewController?
var bottomVC: ChildBottomViewController?
for vc in self.childViewControllers {
if vc is MapViewController {
mapVC = vc as? MapViewController
} else if vc is ChildBottomViewController {
bottomVC = vc as? ChildBottomViewController
}
}
// if we found valid child view controllers, set the delegate
if mapVC != nil && bottomVC != nil {
bottomVC?.cellTapDelegate = mapVC
}
Now, selecting a row from the "slide up from bottom" table view will send the selected indexPath to its delegate - the map view controller.
protocol CellTapDelegate {
func didTapOnItem(obj: MyObject)
}
class MyViewControllerContainingTheTableView : UIViewcontroller {
weak var delegate: CellTapDelegate?
func tableView(_ tableView: UITableView,
didSelectRowAt indexPath: IndexPath) {
let item = arrayOfObjects[indexpath.row]
self.delegate.didTapOnItem(item)
}
}
//View Controller where you you will have the listner
class FirstViewController : UIViewController {
func setupParalax() {
// you have to modify this according to your need
let vc = MyViewControllerContainingTheTableView()
vc.delegate = self
}
}
extension FirstViewController: CellTapDelegate {
func didTapOnItem(obj: MyObject) {
// you have your required object here
}
}
This should be possible by implementing your own delegate, but my knowledge of MMParrallaxView is that there is only 1 view controller which displays two views meaning the view controller should be able to pass things between the two views as it is. In this case the view controller would implement the table view delegate methods and add the table view to the bottom view. Then add the map to the top view. This should allow you to catch the table view cell selection and update the map in the top view accordingly.
Example based on the structure I believe you are using:
public class FirstViewController {
public let parallaxView = MMParallaxView()
private var secondViewController: SecondViewController
private var thirdViewController: ThirdViewController
override open func viewDidLoad() {
secondViewController = SecondViewController()
thirdViewController = ThirdViewController()
super.viewDidLoad()
self.view.addSubview(parallaxView)
thirdViewController.delegate = secondViewController
parallaxView.parallaxTopView = secondViewController.view
self.addChildViewController(secondViewController)
secondViewController.didMove(toParentViewController: self)
parallaxView.parallaxBottomView = thirdViewController.view
self.addChildViewController(thirdViewController)
thirdViewController.didMove(toParentViewController: self)
}
}
public class SecondViewController: ThirdViewControllerDelegate {
public func updateMap() {
// Update map
}
}
public class ThirdViewController: UITableViewDelegate {
weak var delegate ThirdViewControllerDelegate?
private var table: UITableView = UITableView()
open override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
delegate?.updateMap()
}
}
protocol ThirdViewControllerDelegate: class {
public func updateMap() {}
}
if the view controllers are instantiated through the Storyboard then you can try this:
public class MasterViewController {
var secondViewController: SecondViewController?
override func viewDidLoad() {
super.viewDidLoad()
self.performSegue(withIdentifier: "MMParallaxTop", sender: nil)
self.performSegue(withIdentifier: "MMParallaxBottom", sender: nil)
}
override open func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let secondVC = segue.destination as? SecondViewController {
secondViewController = secondVC
}
if let thirdVC = segue.destination as? ThirdViewController, let second = secondViewController {
thirdVC.delegate = second
}
}
}
I have a segue from my MainViewController to my ThemesTableViewController. After performing the segue, I choose a theme on my ThemesTableViewController. When I dismiss my ThemesTableViewController, I want to see the theme selected already applied to my MainViewController. How can I achieve that?
// Here's my Theme
struct Theme {
var name: String!
var backgroundColor: UIColor!
...
}
themes = [red, blue, green]
// I have no idea how I can pass chosenTheme to my MainViewController
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
chosenTheme = themes[indexPath.row]
dismiss(animated: true, completion: nil)
}
protocol ThemeDelegate {
func didSelectTheme(theme: Theme)
}
var delegate: ThemeDelegate?
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
chosenTheme = themes[indexPath.row]
self.delegate?.didSelectTheme(theme: chosenTheme)
}
You can create a protocol and implement it like this and pass the chosenTheme to the previous viewcontroller. In your MainViewController prepare for segue function do it like this.
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
if let themeVC = segue.destination as? ThemesTableViewController {
themeVC.delegate = self
}
}
Also implement an extension like this in MainViewController.
extension MainViewController: ThemeDelegate {
func didSelectTheme(theme: Theme) {
// do something with the selected theme.
}
}
Passing data with unwind segue :
Passing data with unwind segue
Using NotificationCenter for applying theme after unwind :
Adding dark mode to iOS app
I have this:
MyTableViewController (inherits from UITableViewController)
It has a dynamic tableview with a few cells (foo, bar, qux)
MyViewController (inherits from UIViewController)
There are some "show" segues from this controller to other view controllers
It has a UIContainerView that embeds MyTableViewController
A picture speaks a thousand words:
When a certain cell is selected, I want to perform a segue of the parent view (MyViewController)
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
if (indexPath.section == 1 && indexPath.row == 1) {
self.WHAT.performSegueWithIdentifier("someShowSegue1", sender: self)
}
}
Is it possible? what should I use in «WHAT»?
In the prepareForSegue: for your embedded segue set the viewController in a new property in your tableViewController, let's name it parentController. And then you'll have just to call self.parentController.performSegueWithIdentifier().
EDIT: But first of all, maybe you can use the existing parentViewController if it contains the embedding view controller.
You may want to consider using delegation to solve this problem since the child tableView doesn't seem like it should be responsible for the segue. For example:
// MyViewController
class MyViewController: UIViewController, MyTableViewControllerDelegate {
func selectedMyTableViewControllerCell(cell: UITableViewCell) {
// ... check cell type or index or whatever
self.performSegueWithIdentifier("someValueFromCellType", sender: self)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == myTableViewControllerIdentifier {
if let vc = segue.destinationViewController as MyTableViewController? {
vc.delegate = self
}
}
}
}
// MyTableViewController
protocol MyTableViewControllerDelegate: class {
func selectedMyTableViewControllerCell(cell: UITableViewCell)
}
class MyTableViewController: UITableViewController {
weak var delegate: MyTableViewControllerDelegate?
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
// ... get the cell
delegate?.selectedMyTableViewControllerCell(cell)
}
}
No need to create a property. Just this
self.parent?.performSegue(withIdentifier: "ID", sender: self)
SWIFT 4
Swift 4 no longer has parentViewController. You must use parent to access the parent object and is an optional so be sure to check for nil where necessary.
self.parent?.performSegue(withIdentifier: "IdentifierHere", sender: self)
Hook your segue up to the embedded table view controller's cell instead. You can use different segues per cell prototype. This saves you from checking index paths or even implementing didSelectRow at all.
Segue is defined from one view controller to another and is only invoke from the view controller in which it is defined. So you would need to store the reference of the parentViewController.
Like from MyViewController
if ([segueName isEqualToString: #"embedseg"]) {
MyTableViewController * tblViewController = (MyTableViewController *) [segue destinationViewController];
tblViewController.parentController=self; //Storing reference of parentViewController i.e MyViewController
}
Now you can simply invoke segues like
self.parentController.performSegueWithIdentifier("someShowSegue1", sender: self)
Hope this helps
How is it possible to perform a segue from a UITabBarController Child ViewController to a DetailView of an UITableViewController with UINavigationController in between?
There is a TabBarController with two childs, FirstView(Most Viewed Symbol) and NavigationController(Contacts Symbol).
The FirstView has a button, which should perform a segue to Show Profile VC.
The NavCont has a TableView with subclass All ProfilesTVC with a prototype cell as child.
AllProfilesTVC has an array with three names which are displayed by the reused cell.
Which viewcontroller do I have to instantiate and prepare at the function prepareForSegue in FirstView (HomeVC) and where should the segue, which I create in storyboard, direct to? So that I'm at "John's" DetailView.
And is it possible that when I performed a segue to ShowProfileVC, that I can push the Back Button to return to the All ProfilesTVC?
There is a github repo for those who want to try at github repo
FirstView / HomeVC.swift
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// what do we do here ???
}
AllItemsTVC
class AllItemsTVC: UITableViewController {
let profiles = ["Joe", "John", "Ken"]
override func viewDidLoad() {
super.viewDidLoad()
}
// MARK: - Table view data source
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return profiles.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! UITableViewCell
let profile = profiles[indexPath.row] as String
cell.textLabel?.text = profile
return cell
}
#IBAction func cancelFromShowProfile(segue: UIStoryboardSegue) {
}
// MARK: - Navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let identifier = segue.identifier {
switch identifier {
case "ShowProfile":
if let showProfileVC = segue.destinationViewController as? ShowProfileVC {
// pass the data to the destinationVC
let selectedProfile = profiles[tableView.indexPathForSelectedRow()!.row] as String
showProfileVC.name = selectedProfile
}
default: break
}
}
}
ShowProfileVC
class ShowProfileVC: UIViewController {
#IBOutlet weak var textLabel: UILabel! {
didSet {
textLabel.text = name
}
}
var name = "Label"
override func viewDidLoad() {
super.viewDidLoad()
}
}
Thanks for any help.
You cannot do this with a segue, but that's not a problem because you can do it quite simply in code. Just give your view controllers an identifier in storyboard and instantiated them via this identifier with the appropriate UIStoryboard API.
Start by switching to the other tab bar item in code, and then first tell the navigation controller to popToRootViewController, after which you can push all the necessary controllers onto the navigation stack in turn. You can do all the configuration you normally do in prepareForSegue just before pushing the controllers.
The trick is to do it all with animated set to false except the last step.
I have a table view controller with cells. on clicking a cell I load another view controller and I want to handle elements on this view controller. on the detail view controller I placed a label and in the first step I want to set the text of the label, but I get an exception fatal error: unexpectedly found nil while unwrapping an Optional value and I don't know why. Are there any solutions?
This is the part of my table view controller on clicking a cell:
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
let vcMissionDetail : ViewControllerMissionDetail = self.storyboard?.instantiateViewControllerWithIdentifier("MissionDetail") as ViewControllerMissionDetail;
//load detail view controller
self.presentViewController(vcMissionDetail, animated: true, completion: nil)
//set label text
//at this line I get the exception -> label is nil
vcMissionDetail.label.text = "Test"
}
And this is my detail view controller (very simple):
import UIKit
class ViewControllerMissionDetail: UIViewController {
#IBOutlet var label: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
THX!
instantiateViewControllerWithIdentifier returns an optional because it may fail due to several reasons. So you should better unwrap it conditionally:
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
if let vcMissionDetail : ViewControllerMissionDetail = self.storyboard?.instantiateViewControllerWithIdentifier("MissionDetail") as ViewControllerMissionDetail {
//set label text before presenting the viewController
vcMissionDetail.label.text = "Test"
//load detail view controller
self.presentViewController(vcMissionDetail, animated: true, completion: nil)
}
}
Further things to double check:
Is ViewControllerMissionDetail set as the custom class for your viewController in the identity inspector in InterfaceBuilder?
If the vcMissionDetail is successfully instantiated and it still crashes then delete the label's outlet connection in InterfaceBuilder and recreate it.
I think the solution to your problem is pretty straight forward. If I'm understanding correctly, you want to change the label on your detail view controller when you segue from table view controller using the didSelectRowAtIndexPath.
The place where you are probably making a mistake is, you're trying to change the label in your detail view controller from the table view controller.
The correct approach to your problem would be to set the label text in the 'viewDidLoad' or 'viewDidAppear' method of the detail view controller.
override func viewDidLoad() {
super.viewDidLoad()
//set label text here
}
override func viewDidAppear() {
super.viewDidLoad()
//OR set label text here
}
For swift:
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
self.performSegueWithIdentifier("showItemDetail", sender: tableView)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
if segue.identifier == "showItemDetail" {
let indexPath:NSIndexPath = self.tableView.indexPathForSelectedRow()!
let detailVC:ItemDetailViewController = segue.destinationViewController as ItemDetailViewController
detailVC.item = items[indexPath.row] as Item
}
}