Cannot add cell to table view - swift

Question

I'm new to this, I've just made an indexed table view "groups search" with all groups in my app and got a problem: when I'm trying to add some group to the "my groups" view, there are should appear a selected group, but actually I got the first one from all groups array instead. Also I can't add several items started with a similar letter in the "my groups". It might be stupid, but I have no idea how to fix that. Thank you!
import UIKit
final class AllGroupsViewController: UITableViewController {
var groups = [
"cats",
"birds",
"dogs",
"books",
"music",
"movies",
"art",
"science",
"tech",
"beauty",
]
var groupSectionTitles = [String]()
var groupsDictionary = [String: [String]]()
// MARK: - Lifecycle
override func viewDidLoad() {
super.viewDidLoad()
tableView.register(UINib(
nibName: "GroupCell",
bundle: nil),
forCellReuseIdentifier: "groupCell")
for group in groups {
let groupKey = String(group.prefix(1))
if var groupValues = groupsDictionary[groupKey] {
groupValues.append(group)
groupsDictionary[groupKey] = groupValues
} else {
groupsDictionary[groupKey] = [group]
}
}
groupSectionTitles = [String](groupsDictionary.keys)
groupSectionTitles = groupSectionTitles.sorted(by: { $0 < $1 })
}
// MARK: - Table view data source
override func numberOfSections(in tableView: UITableView) -> Int {
return groupSectionTitles.count
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let groupKey = groupSectionTitles[section]
if let groupValues = groupsDictionary[groupKey] {
return groupValues.count
}
return 0
}
override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return groupSectionTitles[section]
}
override func sectionIndexTitles(for tableView: UITableView) -> [String]? {
return groupSectionTitles
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
guard
let cell = tableView.dequeueReusableCell(withIdentifier: "groupCell", for: indexPath) as? GroupCell
else { return UITableViewCell() }
var currentGroup = groups[indexPath.row]
let groupKey = groupSectionTitles[indexPath.section]
if let groupValues = groupsDictionary[groupKey] {
currentGroup = groupValues[indexPath.row]
}
cell.configure(
photo: UIImage(systemName: "person.3.fill") ?? UIImage(),
name: currentGroup)
return cell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
defer { tableView.deselectRow(
at: indexPath,
animated: true) }
performSegue(
withIdentifier: "addGroup",
sender: nil)
}
}
import UIKit
final class MyGroupsViewController: UITableViewController {
var groups = [String]() {
didSet {
//
}
}
#IBAction func addGroup(segue: UIStoryboardSegue) {
guard
segue.identifier == "addGroup",
let allGroupsController = segue.source as? AllGroupsViewController,
let groupIndexPath = allGroupsController.tableView.indexPathForSelectedRow,
!self.groups.contains(allGroupsController.groups[groupIndexPath.section])
else { return }
self.groups.append(allGroupsController.groups[groupIndexPath.section])
tableView.reloadData()
}
// MARK: - Lifecycle
override func viewDidLoad() {
super.viewDidLoad()
tableView.register(UINib(
nibName: "GroupCell",
bundle: nil),
forCellReuseIdentifier: "groupCell")
}
// MARK: - Table view data source
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
groups.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
guard
let cell = tableView.dequeueReusableCell(withIdentifier: "groupCell", for: indexPath) as? GroupCell
else { return UITableViewCell() }
let currentGroup = groups[indexPath.row]
cell.configure(
photo: UIImage(systemName: "person.3.fill") ?? UIImage(),
name: currentGroup)
return cell
}
override func tableView(
_ tableView: UITableView,
commit editingStyle: UITableViewCell.EditingStyle,
forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
groups.remove(at: indexPath.row)
tableView.deleteRows(
at: [indexPath],
with: .fade)
}
}
}

Answer 1

First here is what I understand the goal is:
There is a UITableViewController called MyGroupsViewController which should show all the groups the user has selected
On tapping on + from the MyGroupsViewController, the user is taken to another UITableViewController called AllGroupsViewController which shows all the groups the user can join
On selecting a UITableViewCell from AllGroupsViewController, you will unwind back to MyGroupsViewController showing the groups added for the user
I will say you were quite close and I have just added some minor things which I hope will bring you close to your goal.
One way to pass data between UIViewControllers when using segue transitions is to override a function called prepare for segue (Read more about it in the Apple docs)
1
First change I will make is to add the override prepareForSegue to the end of the MyGroupsViewController class so that I can pass the groups array to the AllGroupsViewController
You can put it anywhere, I added it below your tableview editing function
override func tableView(_ tableView: UITableView,
commit editingStyle: UITableViewCell.EditingStyle,
forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
groups.remove(at: indexPath.row)
tableView.deleteRows(at: [indexPath], with: .fade)
}
}
// This was added by me
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Check the correct segue identifier and retrieve the destination
if segue.identifier == "addGroup",
let allGroupsViewController = segue.destination as? AllGroupsViewController
{
// Set the groups variable with data we stored in the
// user groups array
allGroupsViewController.userGroups = groups
}
}
2
In AllGroupsViewController, I added an array user groups to store all the groups the user taps on and the existing user's groups will be sent to it by MyGroupsViewController in step 1
class AllGroupsViewController: UITableViewController {
var groups = [
"cats",
"birds",
"dogs",
"books",
"music",
"movies",
"art",
"science",
"tech",
"beauty",
]
// I added this. This will save groups the user wants
var userGroups: [String] = []
3.
Then I made some small changes to your tableView didSelectRowAtIndexPath function to store what the user has tapped
override func tableView(_ tableView: UITableView,
didSelectRowAt indexPath: IndexPath) {
defer {
tableView.deselectRow(at: indexPath, animated: true)
}
// Added by me: Retrieve the group tapped by the user
let groupKey = groupSectionTitles[indexPath.section]
var currentGroup = ""
if let groupValues = groupsDictionary[groupKey] {
currentGroup = groupValues[indexPath.row]
}
// Added by me: Check that this group was not added for the user
// before to avoid duplicates
if userGroups.firstIndex(of: currentGroup) == nil {
userGroups.append(currentGroup)
}
self.performSegue(withIdentifier: "addGroup", sender: nil)
}
4
Finally, back in MyGroupsViewController, I updated your addGroup unwind function slightly as follows:
#IBAction func addGroup(segue: UIStoryboardSegue) {
guard segue.identifier == "addGroup",
let allGroupsViewController = segue.source as? AllGroupsViewController
else { return }
// Added by me. Removed old code and added by me. Just update
// the groups array with what was selected in AllGroupsViewController
groups = allGroupsViewController.userGroups
tableView.reloadData()
}
You will get this end result with groups added to the user, without duplicates and also you are able to add groups with the same starting letter.
You can watch the experience here on Youtube
If I missed something or did not answer something from your question, please add some more info / questions in the comments.