Call function in secondFile.swift/viewController from firstFile.swift/viewController? - ios

Question

I'm trying to call a function() made in my first ViewController from another function() made in the second ViewController.
It's a function to update the title of a button in the firstViewController.
I have searched but I can't find a way.
First ViewController // ViewController.swift
import UIKit
class ViewController: UIViewController, UITextFieldDelegate {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
weightLabel.delegate = self
}
#IBAction func excerciseChooserButton(_ sender: UIButton) {
}
var weight = 0 {
didSet {
weightLabel.text = "\(weight)"
}
}
// User input WEIGHT
#IBOutlet weak var weightLabel: UITextField!
func textField(_ weightLabel: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let isNumber = CharacterSet.decimalDigits.isSuperset(of: CharacterSet(charactersIn: string))
let withDecimal = (
string == NumberFormatter().decimalSeparator &&
weightLabel.text?.contains(string) == false
)
return isNumber || withDecimal
}
#IBAction func plusWeight(_ sender: UIButton) {
weight += 5
}
#IBAction func minusWeight(_ sender: UIButton) {
weight -= 5
}
// User input REPS
#IBOutlet weak var repLabel: UILabel!
#IBAction func repSlider(_ sender: UISlider) {
let currentRepValue = Int(sender.value)
repLabel.text = "\(currentRepValue)"
let cm = Calculator(weight: weightLabel.text!, reps: repLabel.text!)
let result = cm.calcRM()
repMax.text = "1RM: \(result)kg"
}
#IBOutlet weak var repMax: UILabel!
#IBOutlet weak var excerciseLabel: UIButton!
func changeText() {
excerciseLabel.setTitle(Excercises.excChosen, for: .normal)
print(excerciseLabel)
}
#IBAction func unwindToViewController(segue:UIStoryboardSegue) {
}
}
// // // //
Second ViewController // ExcerciseChooserViewController.swift
import UIKit
struct Excercises {
static var excChosen:String? = ""
}
class ExcerciseChooserViewController: UIViewController, UITableViewDelegate, UITableViewDataSource
// Data model: These strings will be the data for the table view cells
let excercises: [String] = ["Bench Press", "Squat", "Push Press", "Deadlift"]
// cell reuse id (cells that scroll out of view can be reused)
let cellReuseIdentifier = "cell"
// don't forget to hook this up from the storyboard
#IBOutlet var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
// Register the table view cell class and its reuse id
self.tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellReuseIdentifier)
// (optional) include this line if you want to remove the extra empty cell divider lines
// self.tableView.tableFooterView = UIView()
// This view controller itself will provide the delegate methods and row data for the table view.
tableView.delegate = self
tableView.dataSource = self
}
// number of rows in table view
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.excercises.count
}
// create a cell for each table view row
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
// create a new cell if needed or reuse an old one
let cell:UITableViewCell = self.tableView.dequeueReusableCell(withIdentifier: cellReuseIdentifier) as UITableViewCell!
// set the text from the data model
cell.textLabel?.text = self.excercises[indexPath.row]
return cell
}
// method to run when table view cell is tapped
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let excerciseChosen = "\(excercises[indexPath.row])"
print("You tapped cell number \(indexPath.row).")
print(excerciseChosen)
goBackToOneButtonTapped((Any).self)
Excercises.excChosen = excerciseChosen
print(Excercises.excChosen!)
// call function to update text
ViewController.changeText()
}
#IBAction func goBackToOneButtonTapped(_ sender: Any) {
performSegue(withIdentifier: "unwindToViewController", sender: self)
}
}

Answer 1

Call it from unwindToViewController instead, no need to call it while the first view controller is not visible

Answer 2

There are many ways to do this, but I'll describe a simple one here.
Because you're going back to 'ViewController' via a segue, a good option for you is to override prepare(for:sender:). This will give you a reference to the destination view controller of that segue, which will then allow you to call functions or set properties in that view controller. You can read more about this method here.
Here are some basic steps:
In ViewController, update your changeText() method to accept a string parameter: changeText(_ text: String?).
Add a property to ExcerciseChooserViewController to hold the text you want to use: private var chosenExercise: String?
In your tableView:DidSelectRowAtIndexPath: method, set your new chosenExercise property to the string you want to pass to ViewController.
In prepare(for:sender:) of ExcerciseChooserViewController, grab a reference to destination view controller, downcast it to your subclass ViewController, and call your new method passing in the exerciseText string.
For example:
class ViewController: UIViewController, UITextFieldDelegate {
#IBOutlet weak var excerciseLabel: UIButton!
func changeText(_ text: String?) {
guard let text = text else { return }
excerciseLabel.setTitle(text, for: .normal)
print(excerciseLabel)
}
}
And in ExcerciseChooserViewController:
class ExcerciseChooserViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
private var chosenExercise: String?
// method to run when table view cell is tapped
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let excerciseChosen = "\(excercises[indexPath.row])"
print("You tapped cell number \(indexPath.row).")
print(excerciseChosen)
goBackToOneButtonTapped((Any).self)
Excercises.excChosen = excerciseChosen
print(Excercises.excChosen!)
chosenExercise = excerciseChosen
}
#IBAction func goBackToOneButtonTapped(_ sender: Any) {
performSegue(withIdentifier: "unwindToViewController", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destinationVC = segue.destination as? ViewController {
destinationVC.changeText(chosenExercise)
}
}
}