コメントに詳述されている修正を組み込むためにコードが更新されていることに注意してください。ただし、元の質問テキストは次のとおりです。
状態の復元は、以下のコードベースの ViewController で機能しますが、viewDidLoad への 2 回目の呼び出しによって「元に戻されます」。私の質問は次のとおりです。どうすればそれを回避できますか? ブレークポイントを使用するとdecodeRestorableState、実際には2つのパラメーターが復元されることがわかりますが、その後再びviewDidLoadを通過し、それらのパラメーターはnilにリセットされるため、復元は効果がありません. ストーリーボードはありません。このクラスを空の ViewController に関連付けると機能します (これを再確認しました。ボタン アセットもいくつかありますが、機能には必要ありません)。また、状態の復元を有効にするために必要な AppDelegate メソッドも最後に含めました。selectedGroupselectedType
import UIKit
class CodeStackVC2: UIViewController, FoodCellDel {
let fruit = ["Apple", "Orange", "Plum", "Qiwi", "Banana"]
let veg = ["Lettuce", "Carrot", "Celery", "Onion", "Brocolli"]
let meat = ["Beef", "Chicken", "Ham", "Lamb"]
let bread = ["Wheat", "Muffin", "Rye", "Pita"]
var foods = [[String]]()
let group = ["Fruit","Vegetable","Meat","Bread"]
var sView = UIStackView()
let cellId = "cellId"
var selectedGroup : Int?
var selectedType : Int?
override func viewDidLoad() {
super.viewDidLoad()
restorationIdentifier = "CodeStackVC2"
foods = [fruit, veg, meat, bread]
setupViews()
displaySelections()
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
guard let index = selectedGroup, let type = selectedType else { return }
pageControl.currentPage = index
let indexPath = IndexPath(item: index, section: 0)
cView.scrollToItem(at: indexPath, at: UICollectionViewScrollPosition(), animated: true)
cView.reloadItems(at: [indexPath])
guard let cell = cView.cellForItem(at: indexPath) as? FoodCell else { return }
cell.pickerView.selectRow(type, inComponent: 0, animated: true)
}
//State restoration encodes parameters in this func
override func encodeRestorableState(with coder: NSCoder) {
if let theGroup = selectedGroup,
let theType = selectedType {
coder.encode(theGroup, forKey: "theGroup")
coder.encode(theType, forKey: "theType")
}
super.encodeRestorableState(with: coder)
}
override func decodeRestorableState(with coder: NSCoder) {
selectedGroup = coder.decodeInteger(forKey: "theGroup")
selectedType = coder.decodeInteger(forKey: "theType")
super.decodeRestorableState(with: coder)
}
override func applicationFinishedRestoringState() {
//displaySelections()
}
//MARK: Views
lazy var cView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
layout.minimumLineSpacing = 0
layout.sectionInset = UIEdgeInsets(top: 5, left: 5, bottom: 5, right: 5)
layout.itemSize = CGSize(width: self.view.frame.width, height: 120)
let cRect = CGRect(x: 0, y: 0, width: self.view.frame.width, height: 120)
let cv = UICollectionView(frame: cRect, collectionViewLayout: layout)
cv.backgroundColor = UIColor.lightGray
cv.isPagingEnabled = true
cv.dataSource = self
cv.delegate = self
cv.isUserInteractionEnabled = true
return cv
}()
lazy var pageControl: UIPageControl = {
let pageC = UIPageControl()
pageC.numberOfPages = self.foods.count
pageC.pageIndicatorTintColor = UIColor.darkGray
pageC.currentPageIndicatorTintColor = UIColor.white
pageC.backgroundColor = .black
pageC.addTarget(self, action: #selector(changePage(sender:)), for: UIControlEvents.valueChanged)
return pageC
}()
var textView: UITextView = {
let tView = UITextView()
tView.font = UIFont.systemFont(ofSize: 40)
tView.textColor = .white
tView.backgroundColor = UIColor.lightGray
return tView
}()
func makeButton(_ tag:Int) -> UIButton{
let newButton = UIButton(type: .system)
let img = UIImage(named: group[tag])?.withRenderingMode(.alwaysTemplate)
newButton.setImage(img, for: .normal)
newButton.tag = tag // used in handleButton()
newButton.contentMode = .scaleAspectFit
newButton.addTarget(self, action: #selector(handleButton(sender:)), for: .touchUpInside)
newButton.isUserInteractionEnabled = true
newButton.backgroundColor = .clear
return newButton
}
//Make a 4-item vertical stackView containing
//cView,pageView,subStackof 4-item horiz buttons, textView
func setupViews(){
view.backgroundColor = .lightGray
cView.register(FoodCell.self, forCellWithReuseIdentifier: cellId)
//generate an array of buttons
var buttons = [UIButton]()
for i in 0...foods.count-1 {
buttons += [makeButton(i)]
}
let subStackView = UIStackView(arrangedSubviews: buttons)
subStackView.axis = .horizontal
subStackView.distribution = .fillEqually
subStackView.alignment = .center
subStackView.spacing = 20
//set up the stackView
let stackView = UIStackView(arrangedSubviews: [cView,pageControl,subStackView,textView])
stackView.axis = .vertical
stackView.distribution = .fill
stackView.alignment = .fill
stackView.spacing = 5
//Add the stackView using AutoLayout
view.addSubview(stackView)
stackView.translatesAutoresizingMaskIntoConstraints = false
stackView.topAnchor.constraint(equalTo: view.topAnchor, constant: 5).isActive = true
stackView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
stackView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
stackView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
cView.translatesAutoresizingMaskIntoConstraints = false
textView.translatesAutoresizingMaskIntoConstraints = false
cView.heightAnchor.constraint(equalTo: textView.heightAnchor, multiplier: 0.5).isActive = true
}
// selected item returned from pickerView
func pickerSelection(_ foodType: Int) {
selectedType = foodType
displaySelections()
}
func displaySelections() {
if let theGroup = selectedGroup,
let theType = selectedType {
textView.text = "\n \n Group: \(group[theGroup]) \n \n FoodType: \(foods[theGroup][theType])"
}
}
// 3 User Actions: Button, Page, Scroll
func handleButton(sender: UIButton) {
pageControl.currentPage = sender.tag
let x = CGFloat(sender.tag) * cView.frame.size.width
cView.setContentOffset(CGPoint(x:x, y:0), animated: true)
}
func changePage(sender: AnyObject) -> () {
let x = CGFloat(pageControl.currentPage) * cView.frame.size.width
cView.setContentOffset(CGPoint(x:x, y:0), animated: true)
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let index = Int(cView.contentOffset.x / view.bounds.width)
pageControl.currentPage = Int(index) //change PageControl indicator
selectedGroup = Int(index)
let indexPath = IndexPath(item: index, section: 0)
guard let cell = cView.cellForItem(at: indexPath) as? FoodCell else { return }
selectedType = cell.pickerView.selectedRow(inComponent: 0)
displaySelections()
}
//this causes cView to be recalculated when device rotates
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
cView.collectionViewLayout.invalidateLayout()
}
}
//MARK: cView extension
extension CodeStackVC2: UICollectionViewDataSource, UICollectionViewDelegate,UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return foods.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! FoodCell
cell.foodType = foods[indexPath.item]
cell.delegate = self
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: textView.frame.height * 0.4)
}
}
// *********************
protocol FoodCellDel {
func pickerSelection(_ food:Int)
}
class FoodCell:UICollectionViewCell, UIPickerViewDelegate, UIPickerViewDataSource {
var delegate: FoodCellDel?
var foodType: [String]? {
didSet {
pickerView.reloadComponent(0)
//pickerView.selectRow(0, inComponent: 0, animated: true)
}
}
lazy var pickerView: UIPickerView = {
let pView = UIPickerView()
pView.frame = CGRect(x:0,y:0,width:Int(pView.bounds.width), height:Int(pView.bounds.height))
pView.delegate = self
pView.dataSource = self
pView.backgroundColor = .lightGray
return pView
}()
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
func setupViews() {
backgroundColor = .clear
addSubview(pickerView)
addConstraintsWithFormat("H:|[v0]|", views: pickerView)
addConstraintsWithFormat("V:|[v0]|", views: pickerView)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
if let count = foodType?.count {
return count
} else {
return 0
}
}
func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {
let pickerLabel = UILabel()
pickerLabel.font = UIFont.systemFont(ofSize: 15)
pickerLabel.textAlignment = .center
pickerLabel.adjustsFontSizeToFitWidth = true
if let foodItem = foodType?[row] {
pickerLabel.text = foodItem
pickerLabel.textColor = .white
return pickerLabel
} else {
print("chap = nil in viewForRow")
return UIView()
}
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
if let actualDelegate = delegate {
actualDelegate.pickerSelection(row)
}
}
}
extension UIView {
func addConstraintsWithFormat(_ format: String, views: UIView...) {
var viewsDictionary = [String: UIView]()
for (index, view) in views.enumerated() {
let key = "v\(index)"
view.translatesAutoresizingMaskIntoConstraints = false
viewsDictionary[key] = view
}
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: format, options: NSLayoutFormatOptions(), metrics: nil, views: viewsDictionary))
}
}
AppDelegate の関数は次のとおりです。
//====if set true, these 2 funcs enable state restoration
func application(_ application: UIApplication, shouldSaveApplicationState coder: NSCoder) -> Bool {
return true
}
func application(_ application: UIApplication, shouldRestoreApplicationState coder: NSCoder) -> Bool {
return true
}
func application(_ application: UIApplication, willFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey : Any]? = nil) -> Bool {
//replace the storyboard by making our own window
window = UIWindow(frame: UIScreen.main.bounds)
window?.makeKeyAndVisible()
//this defines the entry point for our app
window?.rootViewController = CodeStackVC2()
return true
}