Move a particular sprite to a target position after clicking the button in unity 4.6 - unity3d

Question

I have just started unity. I have 4 Images(sprites) aligned in a grid.
As soon as i touch the particular chocolate, its texture changes[I wrote a code for that]. There is a button on screen.After pressing the button, I want to move only those chocolates whose texture has been changed.
I know the following move code but i don't know how to use it here.
void Update () {
float step=speed*Time.deltaTime;
transform.position=Vector3.MoveTowards(transform.position,target.position,step);
}
I just don't know to move that particular sprite whose texture is changed. Thanks

Answer 1

Do you want to be moving the sprites over the course of a duration or instantly?
If it's over the course of a duration I suggest you use Lerp. You can Lerp between two Vector.3's in a time scale. Much cleaner and once learned a very useful function.
Code examples below:
http://docs.unity3d.com/ScriptReference/Vector3.Lerp.html
http://www.blueraja.com/blog/404/how-to-use-unity-3ds-linear-interpolation-vector3-lerp-correctly
However if you want to move it instantly. This can be done very easily using the built in localPosition properties which you can set in or outside the object.
Set your changed sprites Bool moved property (create this) to true on click (if you're using Unity 4.6 UI canvas then look at the IClick interfaces available for registering mouse activity in canvas elements) and then when you press the button, loop through a list in a handler file which contains all your button texture objects and move those that the moved property is set to true for.
foreach(GameObject chocolate in chocolateList)
{
if (chocolate.moved == true)
{
gameObject.transform.localPosition.x = Insert your new x position.
gameObject.transform.localPosition.y = Insert your new y position.
}
}
However please do clarify your intentions so I can help further.
EDIT 1:
I highly suggest you make your sprites an object in the canvas for absolute work clarity. This makes a lot of sense as your canvas can handle these type of things much better. Use Image and assign your image the sprite object (your chocolate piece), define it's width and height and add a script to it called "ChocolatePiece", in this script create two public variables, bool moved and int ID, nothing else is required from this script. Save this new object as your new prefab.
Once you've done this in a handler script attached to an empty gameobject in your canvas make a list of gameobjects:
List<GameObject> chocolatePieces = new List<GameObject>();
You'll want to at the top of your handler script define GameObject chocolatePiece and attach in your inspector the prefab we defined earlier. Then in Start(), loop the size of how many chocolate pieces you want, for your example lets use 4. Instantiate 4 of the prefabs you defined earlier as gameobjects and for each define their properties just like this:
Example variables:
int x = -200;
int y = 200;
int amountToMoveInX = 200;
int amountToMoveInY = 100;
Example instantiation code:
GameObject newPiece = (GameObject)Instantiate(chocolatePiece);
chocolatePieces.Add(newPiece);
newPiece.GetComponent<ChocolatePiece>().ID = i;
newPiece.transform.SetParent(gameObject.transform, false);
newPiece.name = ("ChocolatePiece" + i);
newPiece.GetComponent<RectTransform>().localPosition = new Vector3(x, y, 0);
From this point add to your positions (x by amountToMoveInX and y by amountToMoveInY) for the next loop count;
(For the transform.position, each count of your loop add an amount on to a default x and default y value (the position of your first piece most likely))
Now because you have all your gameobjects in a list with their properties properly set you can then access these gameobjects through your handler script.