Swift:如何正确重用 ViewController
Swift: How to reuse a ViewController properly
我得到了一个 UICollectionViewController
类型的 HomeController,它处理一些 PictureCell(包含图片和标签)。
现在我将一个 PictureCell 发送到另一个 ViewController
以编辑标签。这一切都很完美。我可以使用协议将它发送回 HVC,但我不想返回,而是想更进一步并在新 ViewController
.
中显示编辑后的 PictureCell
我没有创建一个全新的,而是将现有的 HomeController 子类化以重用他的 CollectionView
。一切正常,视图显示,但编辑后的 PictureCell 根本没有显示,即使我可以显示它的图层,Cell 本身及其内容也没有显示。
(Messy) Class-图表如下所示:
ClassDiagram
class HomeController: UICollectionViewController, UICollectionViewDelegateFlowLayout, MyProtocol {
override func viewDidLoad() {
super.viewDidLoad()
collectionView?.backgroundColor = UIColor.black
collectionView?.register(PictureCell.self, forCellWithReuseIdentifier: Constants.cellId)
}
//MARK: Get value from second VC
var valueSentFromSecondViewController: String?
var cellSentFromSecondViewController: PictureCell?
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(true)
//Acting with Protocol here
}
//HERE ARE THE COLLECTIONVIEWFUNCTIONS
}
class PictureEditViewController: UIViewController, UITextFieldDelegate {
var delegate:MyProtocol?
var myCell: PictureCell?
let collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
cv.backgroundColor = UIColor.white
return cv
}()
init(pictureCellInit: PictureCell?) {
self.myCell = pictureCellInit
super.init(nibName: nil, bundle: nil)
}
override func viewDidLoad() {
super.viewDidLoad()
showThings()
}
@objc func showNextVC() {
let newViewController = PictureShowViewController(withCell: self.myCell)
newViewController.modalPresentationStyle = .overCurrentContext
present(newViewController, animated: true) //with dismiss
}
@objc func showThings() {
view.addSubview(collectionView)
self.collectionView.frame = CGRect(x: x, y: y, width: width, height: height)
self.setupViews()
}
func setupViews() {
//ADDING THE SUBVIEWS
}
func confBounds() {
//LAYOUT
}
@objc func handleDismiss() {
self.dismiss(animated: true, completion: nil)
}
class PictureShowViewController: HomeController {
//MARK: Variable/Constant declaration
var myCellToShow: PictureCell?
init(withCell: PictureCell?) {
let layoutUsing = UICollectionViewFlowLayout()
myCellToShow = withCell
super.init(collectionViewLayout: layoutUsing)
}
override func viewDidLoad() {
super.viewDidLoad()
collectionView?.backgroundColor = .white
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(true)
collectionView?.addSubview(myCellToShow!)
self.collectionView?.reloadData()
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 1
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = myCellToShow {
cell.layer.borderColor = UIColor.red.cgColor
cell.layer.borderWidth = 2
return cell
}
else {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: Constants.cellId, for: indexPath) as! PictureCell
return cell
}
}
//Size of Cell
override func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let cellSize = CGFloat(view.frame.width)
return CGSize(width: cellSize, height: cellSize)
}
}
有人知道我哪里出错了吗?
使用 PictureCell
在视图控制器中移动数据不是个好主意。 UICollectionView 重用单元格的实例,因此单元格的内容必然会随时更改。
因此,不要使用您的单元格,而是移交基础数据并将数据插入到新出列的集合视图单元格中。
最后,
var cellSentFromSecondViewController: PictureCell?
应该是 var pictureFromSecondViewController: YourPictureData
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: Constants.cellId, for: indexPath) as! PictureCell
//Set your data
cell.picture = pictureFromSecondViewController
return cell
}
我得到了一个 UICollectionViewController
类型的 HomeController,它处理一些 PictureCell(包含图片和标签)。
现在我将一个 PictureCell 发送到另一个 ViewController
以编辑标签。这一切都很完美。我可以使用协议将它发送回 HVC,但我不想返回,而是想更进一步并在新 ViewController
.
我没有创建一个全新的,而是将现有的 HomeController 子类化以重用他的 CollectionView
。一切正常,视图显示,但编辑后的 PictureCell 根本没有显示,即使我可以显示它的图层,Cell 本身及其内容也没有显示。
(Messy) Class-图表如下所示: ClassDiagram
class HomeController: UICollectionViewController, UICollectionViewDelegateFlowLayout, MyProtocol {
override func viewDidLoad() {
super.viewDidLoad()
collectionView?.backgroundColor = UIColor.black
collectionView?.register(PictureCell.self, forCellWithReuseIdentifier: Constants.cellId)
}
//MARK: Get value from second VC
var valueSentFromSecondViewController: String?
var cellSentFromSecondViewController: PictureCell?
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(true)
//Acting with Protocol here
}
//HERE ARE THE COLLECTIONVIEWFUNCTIONS
}
class PictureEditViewController: UIViewController, UITextFieldDelegate {
var delegate:MyProtocol?
var myCell: PictureCell?
let collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
cv.backgroundColor = UIColor.white
return cv
}()
init(pictureCellInit: PictureCell?) {
self.myCell = pictureCellInit
super.init(nibName: nil, bundle: nil)
}
override func viewDidLoad() {
super.viewDidLoad()
showThings()
}
@objc func showNextVC() {
let newViewController = PictureShowViewController(withCell: self.myCell)
newViewController.modalPresentationStyle = .overCurrentContext
present(newViewController, animated: true) //with dismiss
}
@objc func showThings() {
view.addSubview(collectionView)
self.collectionView.frame = CGRect(x: x, y: y, width: width, height: height)
self.setupViews()
}
func setupViews() {
//ADDING THE SUBVIEWS
}
func confBounds() {
//LAYOUT
}
@objc func handleDismiss() {
self.dismiss(animated: true, completion: nil)
}
class PictureShowViewController: HomeController {
//MARK: Variable/Constant declaration
var myCellToShow: PictureCell?
init(withCell: PictureCell?) {
let layoutUsing = UICollectionViewFlowLayout()
myCellToShow = withCell
super.init(collectionViewLayout: layoutUsing)
}
override func viewDidLoad() {
super.viewDidLoad()
collectionView?.backgroundColor = .white
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(true)
collectionView?.addSubview(myCellToShow!)
self.collectionView?.reloadData()
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 1
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = myCellToShow {
cell.layer.borderColor = UIColor.red.cgColor
cell.layer.borderWidth = 2
return cell
}
else {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: Constants.cellId, for: indexPath) as! PictureCell
return cell
}
}
//Size of Cell
override func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let cellSize = CGFloat(view.frame.width)
return CGSize(width: cellSize, height: cellSize)
}
}
有人知道我哪里出错了吗?
使用 PictureCell
在视图控制器中移动数据不是个好主意。 UICollectionView 重用单元格的实例,因此单元格的内容必然会随时更改。
因此,不要使用您的单元格,而是移交基础数据并将数据插入到新出列的集合视图单元格中。
最后,
var cellSentFromSecondViewController: PictureCell?
应该是 var pictureFromSecondViewController: YourPictureData
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: Constants.cellId, for: indexPath) as! PictureCell
//Set your data
cell.picture = pictureFromSecondViewController
return cell
}