Priting each iteration to label

Question

Trying to print out each iteration of Bubblesort to the label text to show on the screen rather than console.

I tried to assign the label text each time the array is updated but it only shows the last version of the array which is the sorted one

On screen print:

on screen print

What I want to print n the label:

what i want to print on the label

class ViewController: UIViewController {

    @IBOutlet weak var Label2: UILabel!

    public func bubbleSort<T> (_ arrays: [T], _ comparison: (T,T) -> Bool) -> [T]  {
        var array = arrays

        for i in 0..<array.count {
            for j in 1..<array.count-i {
                if comparison(array[j], array[j-1]) {
                    let tmp = array[j-1]
                    array[j-1] = array[j]
                    array[j] = tmp
                    print(array) // prints the array after each iteration to the console
                // inserting Label2.text = "\(array)" doesnt work as I intend it to. 
                }
            }
        }


        return array
    }

    public func bubbleSort<T> (_ elements: [T]) -> [T] where T: Comparable {
        return bubbleSort(elements, <)
    }

}

That's not a single label anymore. Probably best to use a UITableView, containing multiple labels. — Alexander, Aug 10 '19 at 02:03
Were you wanting to show all steps on the screen at the same time (similar to the console output), or animate the label showing it change until it is sorted? — vacawama, Aug 10 '19 at 02:14
@vacawama , yes just print the console output to the label or textview. No need for animation at this stage. — ahmeto, Aug 10 '19 at 14:33
I like Alexander's suggestion. Use a tableView to display the results. Create a `[String]` called `steps` to hold the data for the table. At each step, append `steps.append("\(array)")`. Use that as the dataSource for your tableView displaying `cell.label.text = steps[indexPath.row]`. — vacawama, Aug 10 '19 at 14:42
If you want to add multiple lines to a label in a loop then look at [this answer](https://stackoverflow.com/a/57134482/9223839) — Joakim Danielson, Aug 10 '19 at 15:27

score 0 · Accepted Answer · answered Aug 10 '19 at 15:14

This would be a good place to use a tableView to display the data.

Add a UITableView to your ViewController. Add a Basic style prototype cell with "cell" as the reuse identifier.
Attach the tableView in the Storyboard to @IBOutlet var tableView: UITableView!.
Set up the tableView.delegate and tableView.dataSource in viewDidLoad().
Add a property var steps = [String] to your ViewController.
At each step of the bubbleSort, append the array to the steps: steps.append("\(array)").
In numberOfRowsInSection(), return steps.count.
In cellForRowAt(), set cell.textLabel?.text = steps[indexPath.row].
Use a didSet property observer for steps to call tableView.reloadData().

import UIKit

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    @IBOutlet var tableView: UITableView!

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return steps.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)

        cell.textLabel?.text = steps[indexPath.row]

        return cell
    }

    var steps = [String]() {
        didSet {
            tableView.reloadData()
        }
    }

    public func bubbleSort<T> (_ arrays: [T], _ comparison: @escaping (T,T) -> Bool) -> [T]  {
        var array = arrays

        for i in 0..<array.count {
            for j in 1..<array.count-i {
                if comparison(array[j], array[j-1]) {
                    let tmp = array[j-1]
                    array[j-1] = array[j]
                    array[j] = tmp
                    print(array) // prints the array after each iteration to the console
                    steps.append("\(array)")
                }
            }
        }

        return array
    }

    public func bubbleSort<T> (_ elements: [T]) -> [T] where T: Comparable {
        return bubbleSort(elements, <)
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.dataSource = self
        tableView.delegate = self
    }

    @IBAction func go(button: UIButton) {
        steps = []
        _ = bubbleSort([33, 45, 25, 356, 5, 90, 14])
    }
}

Priting each iteration to label

1 Answers1