Overlap and Swapping Images in iOS - ios

Question

I want to swap two images. When I move the drag image and it overlaps 50% or greater on any other image in the view it must be swapped. The problem is how can I check the drag image is 50% or more than 50% overlap with the other image. Please help and suggest the logic with a code example.
The code I am trying is :
if (imgVw.tag != self.tag) {
CGRect imgVwRect = CGRectMake(imgVw.frame.origin.x +(imgVw.frame.size.width/2), imgVw.frame.origin.y+(imgVw.frame.size.height/2), imgVw.frame.size.width, imgVw.frame.size.height);
CGRect movingImgRect = CGRectMake(newCenter.x+self.frame.size.width, newCenter.y+self.frame.size.height, self.frame.size.width, self.frame.size.height);
if (movingImgRect.origin.x >= imgVwRect.origin.x && movingImgRect.origin.y >= imgVwRect.origin.y)
{
NSLog(#"img view tag %lu",imgVw.tag);
UIImage *tempImg = self.image;
[self setImage:imgVw.image];
[imgVw setImage:tempImg];
}
}

Answer 1

This is pretty straightforward.
Use the method CGRectIntersection to calculate the intersection of the 2 rects.
Then compare the area of the intersection with the area of the moving rect. Something like this (assuming I understand your code
if (imgVw.tag != self.tag)
{
CGRect imgVwRect = CGRectMake(imgVw.frame.origin.x +(imgVw.frame.size.width/2),
imgVw.frame.origin.y+(imgVw.frame.size.height/2),
imgVw.frame.size.width,
imgVw.frame.size.height);
CGRect movingImgRect = CGRectMake(newCenter.x+self.frame.size.width,
newCenter.y+self.frame.size.height,
self.frame.size.width,
self.frame.size.height);
//Figure out the intersection rect of the 2 rectangles
CGRect intersectionRect = CGRectIntersection(imgVwRect, movingImgRect);
//Find the area of the intersection
CGFloat xArea = intersectionRect.size.height * intersectionRect.size.width;
//Find the area of the moving image
//(this code could be done once and saved in an iVar)
CGFloat movingImgArea = movingImgRect.size.height * movingImgRect.size.width;
//Is the intersection >= 1/2 the size of the moving image?
if (xArea*2 >= movingImgArea)
{
//Do whatever you need to do when the 2 images overlap by >= 50%
}
}