pinch zoom in collection view - ios

Question

I am trying to add a pinch gesture zoom in my collection view so what is happening is the zoom is happening each time from the start it is not preserving the previous scale state and the max and min scale limit is also not working
since I am new to to swift I am struggling with this, thanks for the help in advance
here is my collection view controller class
import UIKit
class BookViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
#IBOutlet weak var seatMapCollection: UICollectionView!
#IBAction func pinchGesture(_ sender: UIPinchGestureRecognizer) {
}
var dateValue = ["1","2","3","4","10","6","7","8","9","5"]
var dayValue = ["Mon","Tue","Wed","Thu","Thu","Thu","Thu","Thu","Thu","Thu"]
var month = ["jan","feb","mar","apr","Thu","Thu","Thu","Thu","Thu","Thu"]
override func viewDidLoad() {
super.viewDidLoad()
self.seatMapCollection.dataSource = self
self.seatMapCollection.delegate = self
self.seatMapCollection.maximumZoomScale = 2
self.seatMapCollection.minimumZoomScale = 0.50
let pinchGesture = UIPinchGestureRecognizer(target: self, action: #selector(pinchAction(sender:)))
seatMapCollection.addGestureRecognizer(pinchGesture)
self.view.sendSubview(toBack: seatMapCollection)
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
//return seatmapCollection.numberOfItems(inSection: 150)
return 15
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 15
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "SeatMapCollectionViewCell", for: indexPath) as! SeatMapCollectionViewCell
return cell
}
#objc func pinchAction(sender:UIPinchGestureRecognizer){
var scaleValue: CGFloat!
if sender.state == .changed || sender.state == .began {
if scaleValue == nil{
seatMapCollection.transform = CGAffineTransform.init(scaleX: sender.scale, y: sender.scale)
scaleValue = sender.scale
}else{
seatMapCollection.transform = CGAffineTransform.init(scaleX: scaleValue, y: scaleValue)
}
}
}
}
and here is my custom collection view layout class
import UIKit
class CustomCollectionViewLayout: UICollectionViewLayout {
let CELL_HEIGHT = 35.0
let CELL_WIDTH = 35.0
let STATUS_BAR = UIApplication.shared.statusBarFrame.height
var cache = [UICollectionViewLayoutAttributes]()
var contentSize = CGSize.zero
var cellAttrsDictionary = [UICollectionViewLayoutAttributes]()
var cellPadding = 5.0
override var collectionViewContentSize: CGSize {
return self.contentSize
}
var interItemsSpacing: CGFloat = 8
// 5
var contentInsets: UIEdgeInsets {
return collectionView!.contentInset
}
override func prepare() {
// Cycle through each section of the data source.
if collectionView!.numberOfSections > 0 {
for section in 0...collectionView!.numberOfSections-1 {
// Cycle through each item in the section.
if collectionView!.numberOfItems(inSection: section) > 0 {
for item in 0...collectionView!.numberOfItems(inSection: section)-1 {
// Build the UICollectionVieLayoutAttributes for the cell.
let cellIndex = NSIndexPath(item: item, section: section)
let xPos = Double(item) * CELL_WIDTH
let yPos = Double(section) * CELL_HEIGHT
let frame = CGRect(x: xPos, y: yPos, width: CELL_WIDTH, height: CELL_HEIGHT)
let cellFinalAttribute = frame.insetBy(dx:CGFloat(cellPadding) ,dy:CGFloat(cellPadding))
let cellAttributes = UICollectionViewLayoutAttributes(forCellWith: cellIndex as IndexPath)
cellAttributes.frame = cellFinalAttribute
cellAttrsDictionary.append(cellAttributes)
// Determine zIndex based on cell type.
/* if section == 0 && item == 0 {
cellAttributes.zIndex = 4
} else if section == 0 {
cellAttributes.zIndex = 3
} else if item == 0 {
cellAttributes.zIndex = 2
} else {
cellAttributes.zIndex = 1
}*/
// Save the attributes.
//cellAttrsDictionary[cellIndex] = cellAttributes
}
}
}
}
// Update content size.
let contentWidth = Double(collectionView!.numberOfItems(inSection: 0)) * CELL_WIDTH
let contentHeight = Double(collectionView!.numberOfSections) * CELL_HEIGHT
self.contentSize = CGSize(width: contentWidth, height: contentHeight)
}
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
// Create an array to hold all elements found in our current view.
var attributesInRect = [UICollectionViewLayoutAttributes]()
// Check each element to see if it should be returned.
for cellAttributes in cellAttrsDictionary {
if rect.intersects(cellAttributes.frame) {
attributesInRect.append(cellAttributes)
}
}
// Return list of elements.
return attributesInRect
}
override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
return false
}
}
here is my custom cell class
import UIKit
class SeatMapCollectionViewCell: UICollectionViewCell {
#IBOutlet weak var seatDetail: UILabel!
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)!
setup()
}
override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
func setup() {
self.layer.borderWidth = 1.0
self.layer.borderColor = UIColor.gray.cgColor
self.layer.cornerRadius = 5.0
}
}