将 UIPanGestureRecognizer 限制为边界 swift

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)
}

}