Getting the identifier of a touch

I am trying to identify a touch throughout touchesBegan, touchesMoved and touchesEnded.

When printing the UITouch (the entire set) to the console I noticed a String at the beginning, that seems to remain constant for each finger on the screen.

[<UITouch: 0x100d362e0> phase: ...

How do I retrieve this property?

I'm not 100% sure what you are asking but think you can use this as a start to tracking unique touch instances, though I'm not sure how reliable it will be given that we don't create the touch event.

import UIKit

class ViewController: UIViewController {

    var touches: [UITouch] = []

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        self.touches.append(contentsOf: touches)
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        touches.forEach {
            let index = self.touches.index(of: $0)
            print(String.init(describing: index))
        }
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        touches.forEach {
            let index = self.touches.index(of: $0)
            print(String.init(describing: index))
        }
    }
}