问题描述
好吧，所以我想做的是一个图库应用，其中我在一个视图控制器（图像网格）中有一个集合视图，当有人单击图像时，它将加载到具有另一个集合视图的新视图控制器中，然后滑动即可更改图像（手动滑动图像）。 btw图片是从Firebase数据库加载的。
这是我的第一个视图控制器（网格视图），叫它：GridView.swift
import UIKit
import Firebase
import FirebaseDatabase
import SDWebImage
import JJFloatingActionButton
class DoceVC: UIViewController,UICollectionViewDataSource,UICollectionViewDelegate {
@IBOutlet weak var imageCollection: UICollectionView!
let actionButton = JJFloatingActionButton()
var customImageFlowLayout: CustomImageFlowLayout!
var images = [ChudoInsta]()
var dbRef: DatabaseReference!
let viewImageSegueIdentifier = "viewImageSegueIdentifier"
override func viewDidLoad() {
super.viewDidLoad()
dbRef = Database.database().reference().child("wedding/doce_pics")
loadDB()
customImageFlowLayout = CustomImageFlowLayout()
imageCollection.collectionViewLayout = customImageFlowLayout
imageCollection.backgroundColor = .white
actionButton.buttonColor = .black
actionButton.addItem(title: "start slideshow",image: UIImage(named: "largeplay")?.withRenderingMode(.alwaystemplate)) { item in
// do something for testing purpose
print("hello im starting slideshow")
let vc = self.storyboard?.instantiateViewController(identifier: "Slide Show") //as! SlideShowVC
self.navigationController?.pushViewController(vc!,animated: false)
}
actionButton.display(inViewController: self)
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
customImageFlowLayout.setupLayout()
dispatchQueue.main.async {
self.imageCollection.reloadData()
}
}
func loadDB(){
dbRef.observe(DataEventType.value,with: { (snapshot) in
var newImages = [ChudoInsta]()
for chudoInstaSnapshot in snapshot.children {
let chudoInstaObject = ChudoInsta(snapshot: chudoInstaSnapshot as! DataSnapshot)
newImages.append(chudoInstaObject)
}
self.images = newImages
self.imageCollection.reloadData()
})
}
func collectionView(_ collectionView: UICollectionView,numberOfItemsInSection section: Int) -> Int {
return images.count
}
func collectionView(_ collectionView: UICollectionView,cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = imageCollection.dequeueReusableCell(withReuseIdentifier: "Cell",for: indexPath) as! ImageCollectionViewCell
let image = images[indexPath.row]
cell.imageView.sd_setimage(with: URL(string: image.imageUrl),placeholderImage: UIImage(named: "load"))
return cell
}
func collectionView(_ collectionView: UICollectionView,didSelectItemAt indexPath: IndexPath) {
print("ItemSelected \(indexPath)")
//Sending the selected cell(image) from 1st CollectionViewCell(grid) to another second ViewController collectionView.
let vc = self.storyboard?.instantiateViewController(identifier: "DoceFullImageVIew") as! DoceFullImageVIew
vc.path = indexPath.row
self.navigationController?.pushViewController(vc,animated: false)
}
}
这是第二个视图控制器的代码：让我们称之为second.swift
import UIKit
import Firebase
import FirebaseDatabase
import SDWebImage
import Zoomy
class DoceFullImageVIew: UIViewController {
@IBOutlet weak var colltionView: UICollectionView!
var images = [ChudoInsta]()
var dbRef: DatabaseReference!
var path = Int()
let viewImageSegueIdentifier = "doceImageSegueIdentifier"
override func viewDidLoad() {
super.viewDidLoad()
dbRef = Database.database().reference().child("wedding/doce_pics")
loadDB()
}
override func viewDidLayoutSubviews() {
// opening or scrolling to the image from first view controller when the second view controller loads
colltionView.scrollToItem(at:IndexPath(item: path,section: 0),at: .right,animated: false)
}
override func viewWillTransition(to size: CGSize,with coordinator: UIViewControllerTransitionCoordinator) {
super.viewWillTransition(to: size,with: coordinator)
// Have the collection view re-layout its cells.
coordinator.animate(
alongsideTransition: { _ in self.colltionView.collectionViewLayout.invalidateLayout() },completion: { _ in }
)
self.colltionView.reloadData()
}
func loadDB(){
dbRef.observe(DataEventType.value,with: { (snapshot) in
var newImages = [ChudoInsta]()
for chudoInstaSnapshot in snapshot.children {
let chudoInstaObject = ChudoInsta(snapshot: chudoInstaSnapshot as! DataSnapshot)
newImages.append(chudoInstaObject)
}
self.images = newImages
self.colltionView.reloadData()
})
}
func printvalue() {
print("This is the doce full image firebase \(images)")
}
@IBAction func SaveImageDoce(_ sender: Any) {
print("save pressed")
var visibleRect = CGRect()
visibleRect.origin = colltionView.contentOffset
visibleRect.size = colltionView.bounds.size
let visiblePoint = CGPoint(x: CGFloat(visibleRect.midX),y: CGFloat(visibleRect.midY))
let visibleIndexPath = colltionView.indexPathForItem(at: visiblePoint)
print("Visible cell's index is : \(String(describing: visibleIndexPath?.row))!")
let save = self.collectionView(colltionView,cellForItemAt: visibleIndexPath!)
let savepress = save as! DataCollectionViewCell
let dialogMessage = UIAlertController(title: "Confirm",message: "Are you sure you want to Download this image?",preferredStyle: .alert)
// Create OK button with action handler
let ok = UIAlertAction(title: "OK",style: .default,handler: { (action) -> Void in
print("Ok button click...")
UIImageWritetoSavedPhotosAlbum(savepress.img.image!,nil,nil)
})
// Create Cancel button with action handlder
let cancel = UIAlertAction(title: "Cancel",style: .cancel) { (action) -> Void in
print("Cancel button click...")
}
//Add OK and Cancel button to dialog message
dialogMessage.addAction(ok)
dialogMessage.addAction(cancel)
// Present dialog message to user
self.present(dialogMessage,animated: true,completion: nil)
}
}
extension DoceFullImageVIew: UICollectionViewDelegate,UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView,numberOfItemsInSection section: Int) -> Int {
return images.count
}
func collectionView(_ collectionView: UICollectionView,cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell",for: indexPath) as? DataCollectionViewCell
let image = images[indexPath.row]
addZoombehavior(for: cell?.img as! Zoomable)
cell?.img.sd_setimage(with: URL(string: image.imageUrl),placeholderImage: UIImage(named: "load"))
return cell!
}
}
extension DoceFullImageVIew: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView,layout collectionViewLayout: UICollectionViewLayout,sizeforItemAt indexPath: IndexPath) -> CGSize {
let size = collectionView.bounds
return CGSize(width: size.width,height: size.height)
}
func collectionView(_ collectionView: UICollectionView,insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsets(top: 0,left: 0,bottom: 0,right: 0)
}
func collectionView(_ collectionView: UICollectionView,minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
func collectionView(_ collectionView: UICollectionView,minimumLinespacingForSectionAt section: Int) -> CGFloat {
return 0
}
}
所以我的问题是，当我打开第二个视图控制器并滚动到其中的另一个图像并旋转设备时，该图像会自动回滚到初始图像（从第一个视图控制器打开的图像） 。我猜想当旋转发生时，viewDidLoad（）下的代码将再次执行。我怎样才能安全地实现自己的目标？ 这是一个视觉表示：from left to right,how the images scrolls back to initial image after device rotation
解决方法
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