xcode resize and position coordinates - ios

Question

I would like my code (ipad app) to handle resizing of an image by touching it.
I am little confused with how xcode handle points coordinates.
I wrote my code considering that the origin of a frame (frame.origin) is located at the top left (as I read it somewhere), that touches location is the coordinates of the finger touching the screen and that the positive directions are left (x) and up (y). If I am wrong somewhere there that would explain why my code isn't working properly.
Here is my code:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
CGFloat kResizeThumbSize = 45.0f;
touchStart = [[touches anyObject] locationInView:self.view];
CGFloat xO = _ImageView.frame.origin.x;
CGFloat yO = _ImageView.frame.origin.y;
CGFloat width = _ImageView.frame.size.width;
CGFloat height = _ImageView.frame.size.height;
isResizingUD = (xO - kResizeThumbSize < touchStart.x < xO + width + kResizeThumbSize &&
(yO - kResizeThumbSize < touchStart.y < yO + kResizeThumbSize ||
yO - height - kResizeThumbSize < touchStart.y < yO - height + kResizeThumbSize) );
isResizingLR = (yO + kResizeThumbSize < touchStart.x < xO + width - kResizeThumbSize &&
(xO - kResizeThumbSize < touchStart.x < xO + kResizeThumbSize ||
xO - width - kResizeThumbSize < touchStart.x < xO - width + kResizeThumbSize));
}
//moving the image
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
CGPoint touchPoint = [[touches anyObject] locationInView:self.view];
CGPoint previous = [[touches anyObject] previousLocationInView:self.view];
CGFloat deltaWidth = touchPoint.x - previous.x;
CGFloat deltaHeight = touchPoint.y - previous.y;
// get the frame values so we can calculate changes below
CGFloat x = _ImageView.frame.origin.x;
CGFloat y = _ImageView.frame.origin.y;
CGFloat width = _ImageView.frame.size.width;
CGFloat height = _ImageView.frame.size.height;
if (isResizingLR) {
_ImageView.frame = CGRectMake(x, y, width+deltaWidth, height);
} else if (isResizingUD) {
_ImageView.frame = CGRectMake(x, y, width, height+deltaHeight);
} else {
// not dragging from a corner -- move the view
_ImageView.center = CGPointMake(self.view.center.x + touchPoint.x - touchStart.x,
self.view.center.y + touchPoint.y - touchStart.y);
}
}
I would expect the image to be resize in the up/down direction only if the user touch the bottom or the top of the image within kResizeThumbSize (which actually, I am not sure of the unit it is expressed in) and in the right/left direction if the user touch the left or right border of the image within kResizeThumbSize. Unfortunately, what's happen is that the image can be resize in the right/left direction only and wherever I put my finger, it will be resized.
Any help would be greatly welcome.

Answer 1

Fixed!
For anyone needing help for this, I post my code.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
CGFloat kResizeThumbSize = 10.0f;
touchStart = [[touches anyObject] locationInView:self.view];
CGFloat xO = _ImageView.frame.origin.x;
CGFloat yO = _ImageView.frame.origin.y;
CGFloat width = _ImageView.frame.size.width;
CGFloat height = _ImageView.frame.size.height;
isResizingUD = (xO - kResizeThumbSize < touchStart.x &&
touchStart.x < xO + width + kResizeThumbSize &&
yO + height - kResizeThumbSize < touchStart.y);
isResizingLR = (yO + kResizeThumbSize < touchStart.y &&
touchStart.y< yO + height - kResizeThumbSize &&
xO + width - kResizeThumbSize < touchStart.x);
isMoving = (xO+kResizeThumbSize< touchStart.x &&
touchStart.x < xO + width - kResizeThumbSize &&
yO + kResizeThumbSize < touchStart.y &&
touchStart.y< yO + height - kResizeThumbSize);
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
CGPoint touchPoint = [[touches anyObject] locationInView:self.view];
CGPoint previous = [[touches anyObject] previousLocationInView:self.view];
CGFloat deltaWidth = touchPoint.x - previous.x;
CGFloat deltaHeight = touchPoint.y - previous.y;
// get the frame values so we can calculate changes below
CGFloat x = _ImageView.frame.origin.x;
CGFloat y = _ImageView.frame.origin.y;
CGFloat width = _ImageView.frame.size.width;
CGFloat height = _ImageView.frame.size.height;
if (isResizingUD) {
_ImageView.frame = CGRectMake(x, y, width, height+deltaHeight);
} else if (isResizingLR) {
_ImageView.frame = CGRectMake(x, y, width+deltaWidth, height);
} else if (isMoving) {
// not dragging from a corner -- move the view
_ImageView.frame = CGRectMake(x+deltaWidth, y+deltaHeight, width, height);
}
}