How to remove item from Array? - swift

Question

I have a multi selected tableview.
what I am doing : when user select items, this items append to the array.
When user deselect the item from cell, this deselected items remove from array.
what I did :
My array : var selectedTagList:[Tag] = []
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
self.tagTableView.cellForRow(at: indexPath)?.accessoryType = .checkmark
self.selectedTagList.append(tagList![indexPath.row])
}
func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
self.tagTableView.cellForRow(at: indexPath)?.accessoryType = .none
self.selectedTagList.remove(at: indexPath.row)
}
Any advice or sample code please ?
//DataSource and Delegate
extension PickVideoViewController : UITableViewDataSource,UITableViewDelegate {
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
guard let tlist = self.tagList , !tlist.isEmpty else { return 1}
return tlist.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
guard let tlist = self.tagList , !tlist.isEmpty else {
let cell = UITableViewCell()
cell.selectionStyle = .none
cell.backgroundColor = .clear
cell.textLabel?.textAlignment = .center
cell.textLabel?.textColor = UIColor.black
cell.textLabel?.text = "nodataavaiable".localized()
return cell }
let cell = tableView.dequeueReusableCell(withIdentifier: "TagCell", for: indexPath) as! TagCell
cell.tagName.text = tlist[indexPath.row].tag
cell.accessoryType = cell.isSelected ? .checkmark : .none
cell.selectionStyle = .none // to prevent cells from being "highlighted"
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
self.tagTableView.cellForRow(at: indexPath)?.accessoryType = .checkmark
self.selectedTagList.append(tagList![indexPath.row])
}
func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
self.tagTableView.cellForRow(at: indexPath)?.accessoryType = .none
self.selectedTagList.remove(at: <#T##Int#>)
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
guard let tlist = self.tagList , !tlist.isEmpty else {return tableView.frame.height }
return 40
}
}

Answer 1

self.selectedTagList.remove(at: indexPath.row)
indexPath.row is the wrong value to remove. Since your data source populates based on tagList and not selectedTagList, you need to get the item out of tagList and find the equivalent item in selectedTagList.
You don't show what type of object is in tagList, but you will probably need to make them conform to Equatable so you can do this lookup. Once you do, you should have something like this:
let deselectedTag = self.tagList[indexPath.row]
// You will need the items in `tagList` to conform to `Equatable` to do this
guard let indexOfDeselectedTag = self.selectedTagList.index(of: deselectedTag else) {
// Data inconsistency: the item wasn't found in selectedTagList
return
}
self.selectedTagList.remove(at: indexOfDeselectedTag)

Answer 2

You don't need to maintain a list of selected items. You already have all of the items and the tableView can tell you which rows/items are selected.
https://developer.apple.com/documentation/uikit/uitableview/1614864-indexpathsforselectedrows
Discussion
The value of this property is an array of index-path
objects each identifying a row through its section and row index. The
value of this property is nil if there are no selected rows.
You are trying to reinvent the wheel. Always check the documentation for existing functionality.
If you then want a list of selected items from this you just create an array of the items at those index paths, something like this: (untested)
let selectedItems = tableView.indexPathsForSelectedRows().map {
self.tagList[$0.row]
}
This code will iterate over the index paths and return the item from the array at each one. (this is untested, you may need to use flatMap as you are changing the type)