How to pass stepper value to ViewController? - ios

Question

I have a custom cell that has 2 labels, myLabel and numLabel, and a stepper. I have my custom cell in a Swift file and XIB file. I want when I click + or - button on the stepper, my numLabel change with the value of the stepper. I don't know how to pass the stepper value to the viewController where I have my tableView. Later want to save the stepper value to CoreDate how can I do that?. I'm just a beginner. Thank you for helping.
MyCell.swift
import UIKit
class MyCell: UITableViewCell {
static let identifier = "MyCell"
static func nib() -> UINib {
return UINib(nibName: "MyCell", bundle: nil)
}
public func configure(with name: String, number: String) {
myLabel.text = name
numLabel.text = number
}
#IBOutlet var myLabel: UILabel!
#IBOutlet var numLabel: UILabel!
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
}
}
ViewController.swift
import UIKit
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet var table: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
table.register(MyCell.nib(), forCellReuseIdentifier: MyCell.identifier)
table.delegate = self
table.dataSource = self
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 10
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: MyCell.identifier, for: indexPath) as! MyCell
cell.configure(with: "Item 1", number: "1")
return cell
}
}
My Screen Shot

Answer 1

You can do this easily with a "callback" closure:
class MyCell: UITableViewCell {
static let identifier: String = "MyCell"
#IBOutlet var myStepper: UIStepper!
#IBOutlet var numLabel: UILabel!
#IBOutlet var myLabel: UILabel!
// "callback" closure - set my controller in cellForRowAt
var callback: ((Int) -> ())?
public func configure(with name: String, number: String) {
myLabel.text = name
numLabel.text = number
}
#IBAction func stepperChanged(_ sender: UIStepper) {
let val = Int(sender.value)
numLabel.text = "\(val)"
// send value back to controller via closure
callback?(val)
}
static func nib() -> UINib {
return UINib(nibName: "MyCell", bundle: nil)
}
}
Then, in cellForRowAt:
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: MyCell.identifier, for: indexPath) as! MyCell
cell.configure(with: "Item 1", number: "1")
// set the "callback' closure
cell.callback = { (val) in
print("Stepper in cell at \(indexPath) changed to: \(val)")
// do what you want when the stepper value was changed
// such as updating your data array
}
return cell
}

Answer 2

Use a delegate for a generic approach. This allows flexibility in how your cell interacts with the tableview, and enables type checking as you would expect from Swift.
Typically, for a UITableView, you would have an array of data that drives the content of the cells. In your case, let's assume that it's MyStruct (inside your view controller):
struct MyStruct {
let name: String
var value: Int
}
var myStructs: [ MyStruct ] = [
MyStruct( name: "Name 1", value: 1 ),
MyStruct( name: "Name 2", value: 2 ),
MyStruct( name: "Name 3", value: 3 ) ]
Create MyCellDelegate, and place in it whatever methods that you require to communicate changes from the cell to the view controller. For example:
protocol MyCellDelegate: class {
func didSet( value: Int, for myStructIndex: Int )
}
class MyCell: UITableViewCell {
weak var delegate: MyCellDelegate!
var myStructIndex: Int!
...
}
For your table view, assign the delegate when dequeuing the cell, and implement the protocol.
class ViewController: MyCellDelegate, UITableViewDelegate, UITableViewDataSource {
func tableView( _ tableView: UITableView, cellForRowAt indexPath: IndexPath ) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: MyCell.identifier, for: indexPath) as! MyCell
let myStruct = myStructs[indexPath.row] // You may want to ensure that you are in bounds
cell.delegate = self
cell.myStructIndex = indexPath.row
cell.configure( with: myStruct.name, number: myStruct.value )
return cell
}
func didSet( value: Int, for myStructIndex: Int ) {
// Now MyViewController sees the change.
myStructs[myStructIndex].value = value
}
}
Lastly, in your MyCell, whenever the value changes, for example in your stepper, invoke:
#IBAction func stepperChanged( _ sender: UIStepper ) {
let integerValue = Int( sender.value.round() )
numLabel.text = "\(integerValue)"
// Tell the view controller about the change: what happened, and to what cell.
self.delegate.didSet( value: integerValue, for: self.myStructIndex )
}