Dependency injection in uitableviewcell nibs - ios

Question

I'm trying to build a pretty complex table. One cell of this table imports another table. In this imported table I show different rows depending on the situation. The imported table and all the importable table cells are organized into own nib files with own controllers for every cell. As a good programmer I'm trying to use dependency injection throughout the project. The problem now is that when I use the usual way of registering the nibs in viewDidLoad()
let cellNib = UINib(nibName: "BatchConsumptionCell", bundle: nil)
tableView.register(cellNib, forCellReuseIdentifier: "BatchConsumptionCell")
and then use them as dequeueReusableCell(withIdentifier: for:) in tableView(tableView: cellForRowAt:)
let batchConsumptionCell = tableView.dequeueReusableCell(withIdentifier: "BatchConsumptionCell", for: indexPath) as! BatchConsumptionCell
batchConsumptionCell.setConsumption(consumption: consumption)
return batchConsumptionCell
I'm not able to inject the dependencies in time.
In the BatchConsumptionCell all I do in tableView(tableView: cellForRowAt:) works fine. This function is called after dequeueReusableCell(withIdentifier: for:) is executed. But as soon as I'm trying to make the tableView(tableView: numberOfRowsInSection:) dynamic I run into problems. This functions seems to be called before dequeueReusableCell(withIdentifier: for:) so the dependencies are not injected at this point.
I tried to override the init(nibName: bundle:) initializer in my BatchConsumptionCell, but this is a UITableViewCell so I was not able to override this.
How do I approach this? Is there any way I could inject the dependencies as the nib and its controller are initialized? Or do I organize my cells all wrong? Any ideas would be much appreciated.
For more clarity here is my code:
ConsumptionDetailViewController
import UIKit
class ConsumptionDetailViewController: UITableViewController {
// MARK: - Properties
var moc: NSManagedObjectContext!
var consumption: Consumption!
// MARK: - Outlet Properties
#IBOutlet weak var labelDate: UILabel!
#IBOutlet weak var labelTime: UILabel!
...
// MARK: - Default Methods
override func viewDidLoad() {
super.viewDidLoad()
let cellNib = UINib(nibName: "BatchConsumptionCell", bundle: nil)
tableView.register(cellNib, forCellReuseIdentifier: "BatchConsumptionCell")
updateTableFields(selectedConsumption: consumption)
}
// MARK: - UI Update Methods
func updateTableFields(selectedConsumption: Consumption) {
labelId.text = selectedConsumption.wtId
...
}
// MARK: - BatchAddEditDelegate Methods
func didFinishEditing(consumption: Consumption) {
updateTableFields(selectedConsumption: consumption)
}
// MARK: - TableView Methods
override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
...
}
override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
...
}
override func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
...
}
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
...
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if indexPath.section == 1 && indexPath.row == 0 {
let batchConsumptionCell = tableView.dequeueReusableCell(withIdentifier: "BatchConsumptionCell", for: indexPath) as! BatchConsumptionCell
batchConsumptionCell.setConsumption(consumption: consumption)
return batchConsumptionCell
}
return super.tableView(tableView, cellForRowAt: indexPath)
}
// MARK: - Navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
...
}
}
BatchConsumptionCell
import UIKit
class BatchConsumptionCell: UITableViewCell, UITableViewDataSource, UITableViewDelegate {
var consumption: Consumption!
var batchConsumptionCount: Int!
#IBOutlet weak var tableView: UITableView!
override func awakeFromNib() {
super.awakeFromNib()
var cellNib = UINib(nibName: "BatchConsumptionBasicCell", bundle: nil)
tableView.register(cellNib, forCellReuseIdentifier: "BatchConsumptionBasicCell")
cellNib = UINib(nibName: "BatchConsumptionMultiCell", bundle: nil)
tableView.register(cellNib, forCellReuseIdentifier: "BatchConsumptionMultiCell")
self.tableView.delegate = self
self.tableView.dataSource = self
}
func setConsumption(consumption: Consumption) {
self.consumption = consumption
self.batchConsumptionCount = consumption.batchConsumptions?.count
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if batchConsumptionCount == 1 { // <-- This does not work
return 3
} else {
return batchConsumptionCount
}
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if batchConsumptionCount == 1 { // <-- This works fine
let batchConsumptionBasicCell = tableView.dequeueReusableCell(withIdentifier: "BatchConsumptionBasicCell", for: indexPath) as! BatchConsumptionBasicCell
let bc = consumption.batchConsumptions?.allObjects[0] as! BatchConsumption
if indexPath.row == 0 {
batchConsumptionBasicCell.configure(title: "Batch", detail: (bc.batch?.wtId)!)
} else if indexPath.row == 1 {
batchConsumptionBasicCell.configure(title: "Weight", detail: String(describing: bc.weight!))
} else if indexPath.row == 2 {
batchConsumptionBasicCell.configure(title: "Price", detail: String(format:"%.2f", bc.price))
}
} else if batchConsumptionCount >= 2 {
let batchConsumptionMultiCell = tableView.dequeueReusableCell(withIdentifier: "BatchConsumptionMultiCell", for: indexPath) as! BatchConsumptionMultiCell
return batchConsumptionMultiCell
}
return UITableViewCell()
}
}
See the comments // <-- This works fine and
// <-- This does not work in BatchConsumptionCell

Answer 1

You should also register nib to the BatchConsumptionCell class, and implement necessary table view's data source & delegate methods:
class BatchConsumptionCell: UITableViewCell, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var tableView: UITableView!
var consumption: Consumption!
var batchConsumptionCount: Int!
override func awakeFromNib() {
super.awakeFromNib()
var cellNib = UINib(nibName: "BatchConsumptionBasicCell", bundle: nil)
tableView.register(cellNib, forCellReuseIdentifier: "BatchConsumptionBasicCell")
cellNib = UINib(nibName: "BatchConsumptionMultiCell", bundle: nil)
tableView.register(cellNib, forCellReuseIdentifier: "BatchConsumptionMultiCell")
self.tableView.delegate = self
self.tableView.dataSource = self
}
func setConsumption(consumption: Consumption) {
self.consumption = consumption
self.batchConsumptionCount = consumption.batchConsumptions?.count
tableView.reloadData()
}
func numberOfSections(in tableView: UITableView) -> Int {
return consumption == nil ? 0 : 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if batchConsumptionCount == .some(1) { return 3 }
return batchConsumptionCount ?? 0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
switch batchConsumptionCount {
case .some(1):
let batchConsumptionBasicCell = tableView.dequeueReusableCell(withIdentifier: "BatchConsumptionBasicCell", for: indexPath) as! BatchConsumptionBasicCell
let bc = consumption.batchConsumptions?.allObjects[0] as! BatchConsumption
if indexPath.row == 0 {
batchConsumptionBasicCell.configure(title: "Batch", detail: (bc.batch?.wtId)!)
} else if indexPath.row == 1 {
batchConsumptionBasicCell.configure(title: "Weight", detail: String(describing: bc.weight!))
} else if indexPath.row == 2 {
batchConsumptionBasicCell.configure(title: "Price", detail: String(format:"%.2f", bc.price))
}
return batchConsumptionBasicCell
default:
let batchConsumptionMultiCell = tableView.dequeueReusableCell(withIdentifier: "BatchConsumptionMultiCell", for: indexPath) as! BatchConsumptionMultiCell
return batchConsumptionMultiCell
}
}
}