How to recognize a (downwards) swipe gesture

Here is the idea for you:

1. detect the player have touch the screen (with one finger? or 2? or 3? I assume single, but you can set it to something else)

2. catch the initial pos of the finger

3. catch the new pos of the finger in update

4. a simple "if" to detect if the finger has move its pos Y

so here is the code:

private float initialPosY;

 if(Input.touchCount == 1){
             var finger1 = Input.GetTouch(0);
 
             if (finger1.phase == TouchPhase.Began && finger2.phase == TouchPhase.Began){
                 initialPosY = finger1.position.y;
             }else if (finger1.phase == TouchPhase.Moved){
                             float newPosY = finger1.position.y;
                 if(newPosY-initialPosY < xxxx){    //xxxx is the distance you define it as a swipe,
                                  //do something
                             }
             }
         }

if I am correct, upper Y should be larger, so the XXXX should be negative, anyway, please try it yourself.