Dragging an view in limited boundaries not beyond that

Question

After googling a lot and still not finding any solution, I am asking a question.

My question is:- I want to drag my view in a particular area, beyond that, I do not want my view to drag but it should be draggable in the specified view. I am able to achieve to stop dragging if is drags beyond but again when I touches it to drag in the permitted area it does not drag.

My code:-
- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {

        UITouch *touch=[touches anyObject];
        CGPoint pt = [[touches anyObject] locationInView:touch.view];
        startLocation = pt;
    }

    - (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {
        // Move relative to the original touch point
        UITouch *touch=[touches anyObject];
        CGPoint pt = [[touches anyObject] locationInView:touch.view];
        CGPoint pt2 = [[touches anyObject] locationInView:self.view];

        if ([touch.view isKindOfClass:[MyView class]]) {

            CGRect frame = [touch.view frame];
            CGRect prevFrame=[touch.view frame];
            frame.origin.x += pt.x - startLocation.x;
            frame.origin.y += pt.y - startLocation.y;
            CGRect boundsA = [touch.view convertRect:touch.view.bounds toView:nil];
            CGRect boundsB = [self.canvasVw convertRect:self.canvasVw.bounds toView:nil];

                Boolean viewsOverlap = CGRectContainsRect(boundsB,boundsA );
                if (viewsOverlap==YES) {
                    NSLog(@"intersects");
                    [touch.view setFrame:frame];

                }
                else{
                    NSLog(@"not intersects");


    }
        }
      }

The problem in the code is suppose I drag the view , and it goes outside the area then it does not drag again.

See the image:-

I need to drag the red view in only white area not the black area. Please suggest me how to do this. Thanks.

Answer 1

Well, boundaries, basically. As much as boring as it seems, make sure:

• the self.frame.position.x of the red is not < 0 (zero is the position of its parent)
• the self.frame.position.x + self.frame.size.width is not > than self.superview.size.width

The same logic for the Y.

---

Edit 1:

double possibleNewX = pt.x - startLocation.x;

if (((self.frame.position.x + possibleNewX) > 0) && ((self.frame.size.width + self.frame.position.x + possibleNewX) < self.superview.frame.size.width))
{
   frame.origin.x += possibleNewX;
}

double possibleNewY = pt.y - startLocation.y;

if (((self.frame.position.y + possibleNewY) > 0) && ((self.frame.size.height + self.frame.position.y + possibleNewY) < self.superview.frame.size.width))
{
   frame.origin.y += possibleNewY;
}