Question

I’ve got an app where multiple UIImages can be added to the view. Those images can then be dragged around the screen. How can I check which image has been dragged and then save that image’s coordinates to a file and no other UIImage in the same view. I need a way of tagging each UIImage if possible to separate them out and identify them each individually. Hopefully this makes sense!

This is how I’m adding each UIImage to the view:

CGRect imageFrame = CGRectMake(activeView.center.x - 50, activeView.center.y - 50, 200, 200);
imageResizableView = [[SPUserResizableView alloc] initWithFrame:imageFrame];
UIImage *image = [UIImage imageNamed:@"galaxy.jpg"];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
imageResizableView.contentView = imageView;
imageResizableView.delegate = self;
[activeView addSubview:imageResizableView];

Answer 1

UIImageViews are UIView subclasses, so have a tag property. Set that for each image, then when you want that one image [self.subViews viewWithTag:number]; to find it.

EDIT: If I understand this, there are many UIImageViews, but multiple imageViews may show the same image.

Assuming that, then you partition the tag’s 32 bits to say 16 bits upper as the unique imageView number, and the lower 16 are the image number. You will then need to iterate through all subviews looking for the image. You can use macros to make this easier:

#define TAG_NUMBER(imageViewNum, imageNum) ((imageViewNum << 16) | imageNum)
#define IMAGE_FROM_TAG(tag) (tag & 0xFFFF)
etc

when you want to find all imageviews showing that image:

for(UIVIew *view in self.subviews) {
if(![view isKindOf:[UIIMageView class]]) continue;

int imageNum = IMAGE_FROM(view.tag);
if(imageNum == theOneIwant) {
  save frame of "view"
}
}