Simplifying cellForRowAt in TableView - ios

Question

I am writing a personal iOS app to keep track of some things. my app is working well but i am turning my attention to tidying up the code and cleaning things up. in my tableview, one of the cells is uicollectionview that depending on which collectionviewcell I select, a custom tableviewcell is loaded in the same table. At this time I have about a dozen items in my collectionview that i can select from and in turn one of about a dozen different tableviewcells to load. each cell collects different bits of info.
everything is working as i expect it but i don't like the fact that throughout this tableviewcontroller, i have many repetitive sections based on all the tableviewcells i have to handle
override func viewDidLoad() {
super.viewDidLoad()
// register the various tablecells
tableView.register(UINib(nibName: "eventO2TableViewCell", bundle: nil), forCellReuseIdentifier: "eventO2TableViewCell")
...
tableView.register(UINib(nibName: "eventTmpTableViewCell", bundle: nil), forCellReuseIdentifier: "eventTmpTableViewCell")
tableView.register(UINib(nibName: "eventDXTableViewCell", bundle: nil), forCellReuseIdentifier: "eventDXTableViewCell")
similarly cellForRowAt is very big (i.e a switch statement, a dozen cases , each with a corresponding
switch selectedIndexPath.row { // the index of the uicollectionviewcell
case 1:
let cell = tableView.dequeueReusableCell(withIdentifier: "eventTmpTableViewCell", for: indexPath) as! eventTmpTableViewCell
return cell
...
case 11:
let cell = tableView.dequeueReusableCell(withIdentifier: "eventO2TableViewCell", for: indexPath) as! eventO2TableViewCell
return cell
default:
let cell = tableView.dequeueReusableCell(withIdentifier: "eventDXTableViewCell", for: indexPath) as! eventDXTableViewCell
return cell
}
and in
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
another switch statement with a dozen case evaluation to figure out which cell was used and pull out the information i need to save.
was contemplating the idea that was raised in this similar question Is it possible to store custom UITableViewCell into Array? but curious if there are other suggestions ? still consider myself a beginner in this space. thanks

Answer 1

I created extensions for register and deque in UITableView and identifier in UITableViewCell, here is some sample code:
UITableViewExtension.swift
public extension UITableView {
func register<CellClass: UITableViewCell>(_ cellClass: CellClass.Type) {
register(cellClass, forCellReuseIdentifier: cellClass.identifier)
}
func dequeue<CellClass: UITableViewCell>(
_ cellClass: CellClass.Type,
for indexPath: IndexPath,
setup: ((CellClass) -> Void)? = nil) -> UITableViewCell {
let cell = dequeueReusableCell(withIdentifier: cellClass.identifier, for: indexPath)
if let cell = cell as? CellClass {
setup?(cell)
}
return cell
}
}
UITableViewCell.swift
extension UITableViewCell {
static var identifier: String {
return String(describing: self)
}
}
Then in ViewController.swift
class Cell1: UITableViewCell {
// ...
}
class Cell2: UITableViewCell {
// ...
}
class ViewController: UITableViewController {
override func viewDidLoad() {
super.viewDidLoad()
let cells = [Cell1.self, Cell2.self]
tableView.register(cells)
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
return tableView.dequeue(Cell1.self, for: indexPath) { cell in
// customise cell
}
}
}
Note: As you have asked I'm storing UITableViewCells into cells array and get my job done. Even though there are minor changes in our implementations, I hope this will help.

Answer 2

You can create a protocol DequeueInitializable and write its extension like this
import Foundation
import UIKit
protocol DequeueInitializable {
static var reuseableIdentifier: String { get }
}
extension DequeueInitializable where Self: UITableViewCell {
static var reuseableIdentifier: String {
return String(describing: Self.self)
}
static func dequeue(tableView: UITableView) -> Self {
guard let cell = tableView.dequeueReusableCell(withIdentifier: self.reuseableIdentifier) else {
return UITableViewCell() as! Self
}
return cell as! Self
}
static func register(tableView: UITableView) {
let cell = UINib(nibName: self.reuseableIdentifier, bundle: nil)
tableView.register(cell, forCellReuseIdentifier: self.reuseableIdentifier)
}
}
Then in you cell class you confirm to that protocol
class Cell1: UITableViewCell, DequeueInitializable { }
class Cell2: UITableViewCell, DequeueInitializable { }
Now you can register and dequeue cell easily
return Cell1.dequeue(tableView: tableView)
to register
Cell1.register(tableView: tableView)