How would one go about making a transition to a view controller by tapping on a table view cell? My current structure is:
I use a navigation controller as my only way of navigating through my app atm.
I use view models of type struct to represent individual cells. These view models conform to a custom protocol, which consists of a method I call cellSelected.
My question is then: How can I transition to a view controller by tapping on a cell using my cellSelected function? Is this possible?
Custom protocol:
protocol CellRepresentable
{
var reuseIdentier: String { get }
func registerCell(tableView: UITableView)
func cellInstance(of tableView: UITableView, for indexPath: IndexPath) -> UITableViewCell
func cellSelected()
}
Example of a view model:
struct ProfileNameViewModel
{
}
extension ProfileNameViewModel: TextPresentable
{
var text: String
{
return "Name"
}
}
extension ProfileNameViewModel: CellRepresentable
{
var reuseIdentier: String
{
get
{
return ProfileTableViewCell<ProfileNameViewModel>.reuseIdentifier
}
}
func registerCell(tableView: UITableView)
{
tableView.register(ProfileTableViewCell<ProfileNameViewModel>.self, forCellReuseIdentifier: ProfileTableViewCell<ProfileNameViewModel>.reuseIdentifier)
}
func cellInstance(of tableView: UITableView, for indexPath: IndexPath) -> UITableViewCell
{
let cell = tableView.dequeueReusableCell(withIdentifier: reuseIdentier, for: indexPath) as! ProfileTableViewCell<ProfileNameViewModel>
cell.configure(withDelegate: self)
return cell
}
func cellSelected()
{
// ??
}
}
I guess you have a couple of options, you can either pass a reference of your navigation controller to the view model, or you can define a closure that gets executed on cellSelected.
Option 1:
struct ProfileNameViewModel {
private let navigationController: UINavigationController
init(withNavigationController navigationController: UINavigationController) {
self.navigationController = navigationController
}
func cellSelected() {
navigationController.pushViewController(...)
}
}
Option 2:
struct ProfileNameViewModel {
private let selectedAction: () -> Void
init(withSelectedAction selectedAction: #escaping () -> Void) {
self.selectedAction = selectedAction
}
func cellSelected() {
selectedAction()
}
}
and on your view controller:
let vm = ProfileNameViewModel(withSelectedAction: { [weak self] in
self?.navigationContoller?.pushViewController(...)
})
1- Go to Storyboard click on your viewController and in the Utility Area which is on the left side of xcode, and give it a storyboard identifier.
2- go back to you code and execute this in cellSelected()
let say your viewController is called MusicListVC
func cellSelected() {
if let viewController = storyboard?.instantiateViewController(withIdentifier: "your Identifier") as? MusicListVC
{
navigationController?.pushViewController(viewController , animated: true)
}
}
Related
I am trying to recreate the Notes app in iOS. I have created an initial View Controller which is just a table view. A user can go to a Detail View Controller to compose a new note with a Title and Body section. When they click Done, I want to manipulate the tableView with note's details.
I am struggling saving the details of what the user entered to use on my initial view controller.
Here's my Notes class which defines the notes data:
class Notes: Codable {
var titleText: String?
var bodyText: String?
}
Here is the Detail View controller where a user can input Note details:
class DetailViewController: UIViewController {
#IBOutlet var noteTitle: UITextField!
#IBOutlet var noteBody: UITextView!
var noteDetails: Notes?
var noteArray = [Notes]()
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .done, target: self, action: #selector(updateNote))
noteTitle.borderStyle = .none
}
#objc func updateNote() {
noteDetails?.titleText = noteTitle.text
noteDetails?.bodyText = noteBody.text
noteArray.append(noteDetails!) // This is nil
// not sure if this is the right way to send the details over
// let vc = ViewController()
// vc.noteArray.append(noteDetails!)
if let vc = storyboard?.instantiateViewController(identifier: "Main") {
navigationController?.pushViewController(vc, animated: true)
}
}
}
I also have an array on my initial view controller as well. I think I need this one to store note data to display in the tableView (and maybe don't need the one on my Detail View controller?). The tableView is obviously not completely implemented yet.
class ViewController: UITableViewController {
var noteArray = [Notes]()
override func viewDidLoad() {
super.viewDidLoad()
print(noteArray)
self.navigationItem.setHidesBackButton(true, animated: true)
navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .compose, target: self, action: #selector(composeNote))
}
#objc func composeNote() {
if let dvc = storyboard?.instantiateViewController(identifier: "Detail") as? DetailViewController {
navigationController?.pushViewController(dvc, animated: true)
}
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
noteArray.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
return cell
}
Just using Delegate:
First create delegate protocol with a func to send back note to your viewController
protocol DetailViewControllerDelegate: AnyObject {
func newNoteDidAdded(_ newNote: Note)
}
Next add the delegate variable to DetailViewController, and call func noteDataDidUpdate to send data back to viewController
class DetailViewController: UIViewController {
weak var delegate: DetailViewControllerDelegate?
#objc func updateNote() {
....
delegate?.newNoteDidAdded(newNote)
}
}
finally, set delegate variable to viewController and implement this in ViewController
class ViewController: UIViewController {
....
#objc func composeNote() {
if let dvc = storyboard?.instantiateViewController(identifier: "Detail") as? DetailViewController {
dvc.delegate = self
navigationController?.pushViewController(dvc, animated: true)
}
}
}
extension ViewController: DetailViewControllerDelegate {
func newNoteDidAdded(_ newNote: Note) {
// do some thing with your new note
}
}
Stackoverflow
I know how to make a button in the table view cells with website links, rate, mail, and many things. However, How could I open the view controller with the instantiateViewController in the #Objc func's statements?
For example.
Create a new Table View Cell folder called FeedBackButtonsTableViewCell
class FeedBackButtonsTableViewCell: UITableViewCell {
#IBOutlet weak var ButtonCells: UIButton!
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
}
Let create a new view controller folder called
class FeedbackViewController: UIViewController {
#IBOutlet weak var TableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
self.navigationItem.title = "Feedback"
}
}
add the extension to calling the view controller to UITableViewDataSource and UITableViewDelegate and create a obj func statements inside of the second FeedbackViewController with UITableViewDataSource and UITableViewDelegate under the cells.
extension FeedbackViewController: UITableViewDataSource, UITableViewDelegate {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
if indexPath.row == 1 {
buttonCell = TableView.dequeueReusableCell(withIdentifier: "ButtonCells") as? FeedBackButtonsTableViewCell
buttonCell?.ButtonCells.addTarget(self,action: #selector(LearnMore),for: .touchUpInside)
buttonCell?.ButtonCells.tag = indexPath.row
return buttonCell!
}
#objc func LearnMore() {
// How could I write to open the view controller with UIButton in the Table View Cells?
}
}
Thank you for bring a kind of help! :)
Simple solution could be to use procol.
protocol CellActionDelegate{
func didButtonTapped(index: Int)
}
Now confirm the protocol in FeedbackViewController. Take index and actionDelegate properties in your UITableViewCell subclass.
class FeedBackButtonsTableViewCell: UITableViewCell{
var actionDelegate: CellActionDelegate?
var index: Int?
.....
// Take Action of UIButton here
#IBAction func more(_ sender: Any) {
if let delegate = self.actionDelegate{
delegate.didButtonTapped(index!)
}
}
}
Now in your FeedbackViewController set actionDelegate & Corresponding index in
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {}
you can open anotherView controller from func didButtonTapped(index: Int) definition .
extension FeedbackViewController:CellActionDelegate{
func didButtonTapped(index: Int) {
let storybord = UIStoryboard(name: "Main", bundle: nil)
guard let controller = storybord.instantiateViewController(withIdentifier: "AnotherControllerIdentfier") as? AnotherViewController else{
fatalError("Could not finc another view controller")
}
self.present(controller, animated: true, completion: nil)
}
}
#objc func LearnMore() {
let viewController = FeedbackDetailsViewController()// creation of viewController object differs depends on how you fetch the UI, means either you are using storyboard or xib or directly making ui in code.
self.navigationController?.pushViewController(viewController, animated: true)
}
Here is the code with the delegate process suggested...
in main view controller...
protocol FilterDelegate: class {
func onRedFilter()
func onGreenFilter()
func onBlueFilter()
func onUnfiltered()
}
class ViewController: UIViewController, FilterDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
----
// Increase red color level on image by one.
func onRedFilter() {
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "filterSegue" {
let dest = segue.destinationViewController as! CollectionViewController
dest.filterDelegate = self
}
}
in collection view controller...
var filterDelegate: FilterDelegate?
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
print("Cell \(indexPath.row) selected")
guard let filterDelegate = filterDelegate else {
print("Filter delegate wasn't set!")
return
}
switch indexPath.row {
case 0:
filterDelegate.onRedFilter()
case 1:
filterDelegate.onGreenFilter()
case 2:
filterDelegate.onBlueFilter()
case 3:
filterDelegate.onUnfiltered()
default:
print("No available filter.")
}
Right now...the code stops at the guard block and prints the error message. The switch block is not executed on any press of a cell.
Your theory in your second last sentence is correct - when you call storyboard.instantiateViewControllerWithIdentifier in the "child" view controller, you are actually creating an entirely new instance of your main view controller. You are not getting a reference to the existing main view controller, which is why the methods you're calling are not having any effect.
There are several ways to achieve what you're trying to do, including the delegate pattern or using closures. Here's a sketch of what it could look like using a delegate protocol:
protocol FilterDelegate: class {
func onRedFilter()
func onGreenFilter()
func onBlueFilter()
func onUnfiltered()
}
class MainViewController: UIViewController, FilterDelegate {
// implement these as required
func onRedFilter() { }
func onGreenFilter() { }
func onBlueFilter() { }
func onUnfiltered() { }
// when we segue to the child view controller, we need to give it a reference
// to the *existing* main view controller
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let dest = segue.destination as? ChildViewController {
dest.filterDelegate = self
}
}
}
class ChildViewController: UIViewController {
var filterDelegate: FilterDelegate?
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
// ...
guard let filterDelegate = filterDelegate else {
print("Filter delegate wasn't set!")
return
}
switch indexPath.row {
case 0:
filterDelegate.onRedFilter()
case 1:
filterDelegate.onGreenFilter()
case 2:
filterDelegate.onBlueFilter()
case 3:
filterDelegate.onUnfiltered()
default:
print("No available filter.")
}
}
}
Another option would be to provide closures on ChildViewController for every function on MainViewController that the child needs to call, and set them in prepareForSegue. Using a delegate seems a bit cleaner though since there are a bunch of functions in this case.
I have a View1 when i click on textbox i am going to view2(table view) to pick a value. I want to send the picked value to view1 for that textbox.
The controls are created programmatically so i am not using segue,IBActions.
I am trying to use the protocol methods still no success. Here is what i have tried.
class DynamicSuperView: UIViewController,UITableViewDelegate,UITableViewDataSource,dropdownDelegate,UITextFieldDelegate
{
func setValue(value:AnyObject)
{
print("dynamic view delegate method executed")
self.labelText = value as! String
//return selectedValue;
}
override func viewDidLoad() {
}
}
The second class is here with delegate method..
protocol dropdownDelegate {
func setValue(value: AnyObject);
}
class testClass: UIViewController,UITableViewDataSource,UITableViewDelegate,UISearchBarDelegate {
var delegate:dropdownDelegate! = nil
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let vcName = names[indexPath.row]
print ("Table view cell clicked and value passed: \(vcName)")
if let cell = tableView.cellForRow(at: indexPath) {
cell.accessoryType = .checkmark
}
self.navigationController?.popViewController(animated: true)
delegate.setValue(value: "Testing delegate")
}
}
Once i select the value in the tableview i am calling the delegate method and trying to pass that value but no success.
I don't want to create the new instance of the previous view controller because i will lose the data already entered by the user, so i am popping the current view controller and going to the previous view controller.
Please suggest if my approach i correct or not?
ERROR:
fatal error: unexpectedly found nil while unwrapping an Optional value
Thank you in advance
Try this:
view func ButtonPressed() {
print("Button Pressed!!") // This will create the new instance of the view controller.
let vc = UIStoryboard(name:"Main", bundle:nil).instantiateViewController(withIdentifier: "Storage") as! testClass
vc.delegate = self
self.navigationController?.pushViewController(vc, animated:true)
}
You are not setting the delegate to first view controller.
I have a function within a UICollectionViewCell that requires access to the
hosting UIViewController. Currently 'makeContribution()' can't be accessed:
What is the proper way of accessing the host UIViewController that has the desired function?
Thanks to the insightful responses, here's the solution via delegation:
...
...
...
{makeContribution}
This is a mildly controversial question - the answer depends a little on your philosophy about MVC. Three (of possibly many) options would be:
Move the #IBAction to the view controller. Problem solved, but it might not be possible in your case.
Create a delegate. This would allow the coupling to be loose - you could create a ContributionDelegate protocol with the makeContribution() method, make your view controller conform to it, and then assign the view controller as a weak var contributionDelegate: ContributionDelegate? in your cell class. Then you just call:
contributionDelegate?.makeContribution()
Run up the NSResponder chain. This answer has a Swift extension on UIView that finds the first parent view controller, so you could use that:
extension UIView {
func parentViewController() -> UIViewController? {
var parentResponder: UIResponder? = self
while true {
if parentResponder == nil {
return nil
}
parentResponder = parentResponder!.nextResponder()
if parentResponder is UIViewController {
return (parentResponder as UIViewController)
}
}
}
}
// in your code:
if let parentVC = parentViewController() as? MyViewController {
parentVC.makeContribution()
}
Well, CollectionView or TableView?
Anyway, Set your ViewController as a delegate of the cell. like this:
#objc protocol ContributeCellDelegate {
func contributeCellWantsMakeContribution(cell:ContributeCell)
}
class ContributeCell: UICollectionViewCell {
// ...
weak var delegate:ContributeCellDelegate?
#IBAction func contributeAction(sender:UISegmentedControl) {
let isContribute = (sender.selectedSegmentIndex == 1)
if isContribute {
self.delegate?.contributeCellWantsMakeContribution(self)
}
else {
}
}
}
class ViewController: UIViewController, UICollectionViewDataSource, ContributeCellDelegate {
// ...
func collectionView(_ collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
cell = ...
if cell = cell as? ContributeTableViewCell {
cell.delegate = self
}
return cell
}
// MARK: ContributeCellDelegate methods
func contributeCellWantsMakeContribution(cell:ContributeCell) {
// do your work.
}
}