Limit UIPanGestureRecognizer to boundaries swift - ios

Question

I have a images inside uicollectionview cell which scroll horizontally, I want to achieve a feature like the facebook and photo app apple, you click on image and it covers the whole screen. You can pinch and pan the image, I want to add certain limitations same like the facebook and photo app, like when you pinch the picture you can pan maximum to its width.
I want the image to recenter again if user try to move image out of the boundaries. I am adding some screenshots to give idea about it.
Right now I am using the simple code.
guard gestureRecognizer.view != nil else {return}
print(self.imgView.frame)
if self.imgView.frame.size.width < (self.imgOrignal.width+100) {
return
}
let piece = gestureRecognizer.view!
// Get the changes in the X and Y directions relative to
// the superview's coordinate space.
let translation = gestureRecognizer.translation(in: piece.superview)
if gestureRecognizer.state == .began {
self.initialCenter = piece.center
}
// Update the position for the .began, .changed, and .ended states
if gestureRecognizer.state != .cancelled {
// Add the X and Y translation to the view's original position.
let newCenter = CGPoint(x: initialCenter.x + translation.x, y: initialCenter.y + translation.y)
piece.center = newCenter
}
else {
// On cancellation, return the piece to its original location.
piece.center = initialCenter
}
}

Answer 1

I have resolved this issue by using UIScrollView zoom in and out, instead of using pinch and pan gesture, If any one wants to implement that functionality i am adding my code below.
func setZoomScale() {
let widthScale = self.bgView.frame.size.width / self.imgView.bounds.width
let heightScale = self.bgView.frame.size.height / self.imgView.bounds.height
let minScale = min(widthScale, heightScale)
self.imgScrollView.minimumZoomScale = minScale
self.imgScrollView.zoomScale = minScale
}
extension YOUR CLASS: UIScrollViewDelegate {
func viewForZooming(in scrollView: UIScrollView) -> UIView? {
return self.imgView
}
func scrollViewDidZoom(_ scrollView: UIScrollView) {
let imageViewSize = self.imgView.frame.size
let scrollViewSize = scrollView.bounds.size
let verticalInset = imageViewSize.height < scrollViewSize.height ? (scrollViewSize.height - imageViewSize.height) / 2 : 0
let horizontalInset = imageViewSize.width < scrollViewSize.width ? (scrollViewSize.width - imageViewSize.width) / 2 : 0
scrollView.contentInset = UIEdgeInsets(top: verticalInset, left: horizontalInset, bottom: verticalInset, right: horizontalInset)
}
}