Swipe Gesture iOS

Questions & Answers
1

Ive been looking around for a script that will detect horizontal swipe gestures. I have found a few examples but they dont work. If someone can post this it would be greatly appreciated.

2

Here’s some code I threw together the other day to answer a similar question.

I’m sure it will need to be altered, but it’s a good start.

It works surprisingly well (but not great) when I do an iPad build.

Note:

This is just an example script intended to demonstrate the basic concept.

Here’s the idea:

  • define a speed threshold: the minimum speed that determines a swipe
  • each frame that has touchCount == 1, check if the speed is greater than the threshold
  • if it is (and it wasn’t the last frame) store the start position
  • if it is not (and it was the last frame) store end position and/or do stuff (swipe is complete)

Here’s some tested exactly twice code:

var  swipeThresh      :    float  =   1.2;
var  swipeStart       :  Vector2  =   Vector2.zero;
var  swipeEnd         :  Vector2  =   Vector2.zero;
var  swipeWasActive   :  boolean  =   false;

function Update ()
{
    if ( Input.touchCount == 1 ) {
        processSwipe();
    }
}

function OnGUI ()
{
    processSwipe();
    drawStartBox();
    drawEndBox();
}

function processSwipe ()
{
    if ( Input.touchCount != 1 ) {
        return;
    }

    var theTouch : Touch = Input.touches[0];

    /* skip the frame if deltaPosition is zero */

    if ( theTouch.deltaPosition == Vector2.zero ) {
        return;
    }

    var speedVec : Vector2 = theTouch.deltaPosition * theTouch.deltaTime;
    var theSpeed :   float = speedVec.magnitude;

    var swipeIsActive : boolean = ( theSpeed > swipeThresh );

    if ( swipeIsActive ) {

        if ( ! swipeWasActive ) {
            swipeStart = theTouch.position;
        }
    }

    else {

        if ( swipeWasActive ) {
            swipeEnd = theTouch.position;
            Debug.Log("Swipe Complete");
        }
    }

    swipeWasActive = swipeIsActive;
}

function drawStartBox ()
{
    if ( swipeStart == Vector2.zero ) {
        return;
    }

    /* don't forget to invert the y-coordinate */

    var theY = Screen.height - swipeStart.y;
    var theX = swipeStart.x;

    var theRect : Rect = Rect(theX, theY, 140, 40);

    GUI.Label(theRect, "Start");
}

function drawEndBox ()
{
    if ( swipeEnd == Vector2.zero ) {
        return;
    }

    /* don't forget to invert the y-coordinate */

    var theY = Screen.height - swipeEnd.y;
    var theX = swipeEnd.x;

    var theRect : Rect = Rect(theX, theY, 140, 40);

    GUI.Label(theRect, "End");
}

I just gave this a try and it works surprisingly well…

I used a speed threshhold of 1.2, which can be adjusted in the Inspector.

Hope this helps!