Move UIImage by touchmove in increment of 20 pixels X-coord or Y-coord.

Question

Hi. I'm quite new to programming and i having a problem right now figuring out some methods on my program. anyways i cant figure out how to work out my touchmove event. I want to move a uiimage in x direction or y direction depending on the direction of the touchmove event but i want the movement to be in a grid type movement like by 20 pixels. i use touchbegan to check what image is touch;

    - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];

if(CGRectContainsPoint(image1.frame,location))
    image1IsDragging = YES;
else
    image2IsDragging=NO;

}

and i got stuck with my touchmoved event.

     - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];

    if (image1IsDragging == YES) {
    //stuck here on how to check the direction of the swipe and how to move in increment of 20 pixs
   }

}

I was thinking of getting the round-off of the distance like;

float distanceX = newLocation.x - firstTouch.x;

but i dont know how to do it. Hope someone could lend me some help. thanks.

Answer 1

For direction of touch, see: http://stackoverflow.com/questions/541962/detecting-special-touch-on-the-iphone