【发布时间】：2021-01-09 11:08:45
【问题描述】：
我现在尝试了几天，但还没有取得任何成果。我想要做的是当用户从 ViewController 类中选择一个 User 项目时，我想将它保存在 Realm 中并在 SavedInterestsViewController 类的 CollectionView 中显示它。我使用了这篇文章How to access and refresh a UITableView from another class in Swift 中建议的委托模式，但不幸的是我仍然收到 nil，我猜是因为 GC 已经删除了 collectionView 出口，对吧？ （如果我误解了，请纠正我）。但是，我怎样才能通过使用委托模式来实现它呢？这是我的代码，这是用户选择新用户项的类：
protocol ViewControllerDelegate {
func didUpdate(sender: ViewController)
}
class ViewController: UIViewController {
@IBOutlet weak var searchBar: UISearchBar!
@IBOutlet weak var collectionView: UICollectionView!
var delegate: ViewControllerDelegate?
let numberOfTweets = 5
let realm = try! Realm()
var image = UIImage()
var imageArray: [String] = []
var userArray: [User] = []
override func viewDidLoad() {
super.viewDidLoad()
collectionView.delegate = self
collectionView.dataSource = self
collectionView.register(UINib(nibName: "CollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "CollectionCell")
searchBar.delegate = self
}
}
extension ViewController: UISearchBarDelegate {
func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
print("One second...")
let functionClass = NetworkingFunctions()
var loopCount = 0
functionClass.getWikipediaAssumptions(for: searchBar.text!) { [self] (articleArray) in
self.userArray.removeAll()
for x in articleArray {
functionClass.performWikipediaSearch(with: x, language: WikipediaLanguage("en")) { (user) in
self.userArray.append(user)
collectionView.reloadData()
loopCount += 1
}
}
}
}
}
extension ViewController: UICollectionViewDelegate, UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return userArray.count
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionCell", for: indexPath) as! CollectionViewCell
let image = UIImage.init(data: userArray[indexPath.item].image as Data)
cell.userImage.image = image
cell.nameLabel.text = userArray[indexPath.item].name
cell.userImage.layer.borderColor = image?.averageColor?.cgColor
if userArray[indexPath.item].checked == false {
cell.checkmark.isHidden = true
} else {
cell.checkmark.isHidden = false
}
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
if userArray[indexPath.item].checked == false {
userArray[indexPath.item].checked = true
collectionView.reloadData()
let newUser = User()
newUser.image = userArray[indexPath.item].image
newUser.name = userArray[indexPath.item].name
newUser.checked = true
try! realm.write {
realm.add(newUser)
}
self.delegate = SavedInterestsViewController()
self.delegate?.didUpdate(sender: self)
}
else {
userArray[indexPath.item].checked = false
collectionView.reloadData()
}
}
}
extension ViewController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let width = UIScreen.main.bounds.width/3 - 10
let height = width
return CGSize(width: width, height: height)
}
}
class User: Object {
@objc dynamic var image: NSData = NSData()
@objc dynamic var name: String = ""
@objc dynamic var checked: Bool = false
}
...这是我想要显示所选项目的类，在用户单击 ViewController 类的导航控制器的“后退”按钮后：
class SavedInterestsViewController: UIViewController, ViewControllerDelegate {
func didUpdate(sender: ViewController) {
DispatchQueue.main.async {
self.collectionView.reloadData()
}
}
@IBOutlet weak var addButton: UIBarButtonItem!
@IBOutlet weak var collectionView: UICollectionView!
let realm = try! Realm()
var userArray: [User] = []
override func viewDidLoad() {
super.viewDidLoad()
collectionView.delegate = self
collectionView.dataSource = self
collectionView.register(UINib(nibName: "CollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "CollectionCell")
fetchDataFromRealm()
}
@IBAction func addButtonPressed(_ sender: UIBarButtonItem) {
performSegue(withIdentifier: "SavedToNew", sender: self)
}
func fetchDataFromRealm() {
userArray.append(contentsOf: realm.objects(User.self))
collectionView.reloadData()
}
}
extension SavedInterestsViewController: UICollectionViewDelegate, UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return userArray.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionCell", for: indexPath) as! CollectionViewCell
let image = UIImage.init(data: userArray[indexPath.item].image as Data)
cell.userImage.image = image
cell.nameLabel.text = userArray[indexPath.item].name
cell.userImage.layer.borderColor = image?.averageColor?.cgColor
if userArray[indexPath.item].checked == false {
cell.checkmark.isHidden = true
} else {
cell.checkmark.isHidden = false
}
return cell
}
}
extension SavedInterestsViewController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let width = UIScreen.main.bounds.width/3 - 10
let height = width
return CGSize(width: width, height: height)
}
}
【问题讨论】：
标签： swift collections