Drag UIImageView and Drop in another UIImageView - ios

Question

I have a UIScrollView that contains n number of placeholder UIImageView's. Below that i have a StackView containing 10 images that the user will choose from and drag an image to a specific placeholder image view above. I have the PanGesture implemented and that works fine, however, i'm struggling with how to detect when the draggable image is within the bounds of a placeholder image. Especially since it is in a scroll view. I was able to get it to some what work with the center.X and center.Y of the draggable views then checking those values against their relative values of the placeholders, but it did not work as desired. And from what i can see, the X and Y coordinates from dragging, only apply to the actual parent UIView. So, when an image is dragged into the scroll view, the X values don't necessarily line up, some of those placeholder image X coordinates may be 2000+ if the list is long. Take a look at the code below and let me know your thoughts and suggestions. Thanks!
#IBAction func handlePan(recognizer:UIPanGestureRecognizer) {
let translation = recognizer.translationInView(self.view)
if recognizer.state == UIGestureRecognizerState.Began {
originalViewLocation = recognizer.view!.center
}else if recognizer.state == UIGestureRecognizerState.Ended {
for placeHolderView in playerImages{
if ((recognizer.view!.center.x < (placeHolderView.center.x + (placeHolderView.frame.width / 2)) && recognizer.view!.center.x > placeHolderView.frame.origin.x)){
if recognizer.view!.center.y < (stackView.center.y + stackView.frame.height / 2){
let chosenImage = recognizer.view! as! UIImageView
placeHolderView.image = chosenImage.image
}
}else{
UIView.animateWithDuration(0.5, delay: 0.0, options: .CurveEaseInOut, animations: {
recognizer.view!.center = self.originalViewLocation
}, completion: { finished in
})
}
}
}
if let view = recognizer.view {
view.center = CGPoint(x:view.center.x + translation.x,
y:view.center.y + translation.y)
}
recognizer.setTranslation(CGPointZero, inView: self.view)
print("X: \(recognizer.view!.center.x)")
print("Y: \(recognizer.view!.center.y)")
}
The playerImages array stores the UIImageViews in the scroll view.

Answer 1

Well i did solve this on my own. It had to do with the relative coordinate values vs actual coordinate values.
I ended up needing a few things...
CGRectContainsPoint()
To check whether or not the frame of the destination placeholder view contains the center point of the dragging view.
And...
convertRect()
with
convertPoint()
I had to convert the coordinate values of the dragging point to the values of the superview. Along with, converting the frame values of the placeholder views within the scroll view, to the same (superview values). Like so...
let convertedCenter = recognizer.view!.superview!.convertPoint(recognizer.view!.center, toView: self.view)
let convertedFrame = self.view.convertRect(IV.frame,fromView: IV.superview)
if CGRectContainsPoint(convertedFrame, convertedCenter) {
//Replace placeholder image with dragged image.
}
Hopefully this will help someone else.