multitouch in iOS

Question

We're developing an application that calculates the distance between multiple finger touches. so the method 'touchesBegan' gets the coordination of these touches points.

the problem is that when I enable the multitouch property, the method must receive the touches simultaneously or it won't work if some delay happens between your two fingers means that there's a possibility of missing one or more touches. We need a way to detect all the points before calculating the distance.

this is part of the code

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    var loc1X:CGFloat?
    var loc1Y:CGFloat?
    var loc2X:CGFloat?
    var loc2Y:CGFloat?
    var locations = [CGPoint]()



    if touches.count == 2{
        // errorLabel.text = " "
        for touch in touches {

            locations.append(touch.location(in: self.view))
        }
        loc1X=locations[0].x
        loc1Y=locations[0].y
        loc2X=locations[1].x
        loc2Y=locations[1].y
        distance1 = sqrt(pow((loc2X! - loc1X!), 2) + pow((loc2Y! - loc1Y!), 2))
        print(distance1)

Thanks