我的应用程序中有一个视频播放器。集合视图中有一个视频列表。如果您点击其中一个单元格，则会出现一个新的视图控制器来播放所选视频。此外，您还可以在这个新视图控制器中循环浏览集合视图中的所有视频，因为整个列表都会被传递。
问题是：
当用户处于PlayerVC，他们可以取消收藏Video。如果他们这样做，我会删除Video来自 Realm 的对象。然而，这会导致：
Terminating app due to uncaught exception 'RLMException', reason: 'Object has been deleted or invalidated.'
基本上，如果用户正在观看视频PlayerVC他取消了某个视频的收藏，我希望他们暂时仍能观看该视频。但当他们离开PlayerVC，集合视图FavoritesVC应该更新并且不显示Video不再有。
当我删除一个Video我使用 Realm 的对象delete method.
这是我的代码来保存列表Video对象：
/// Model class that manages the ordering of `Video` objects.
final class FavoriteList: Object {
// MARK: - Properties
/// `objectId` is set to a static value so that only
/// one `FavoriteList` object could be saved into Realm.
dynamic var objectId = 0
let videos = List<Video>()
// MARK: - Realm Meta Information
override class func primaryKey() -> String? {
return "objectId"
}
}
这是我的Video类有一个isFavorite财产：
final class Video: Object {
// MARK: - Properties
dynamic var title = ""
dynamic var descriptionText = ""
dynamic var date = ""
dynamic var videoId = ""
dynamic var category = ""
dynamic var duration = 0
dynamic var fullURL = ""
dynamic var creatorSite = ""
dynamic var creatorName = ""
dynamic var creatorURL = ""
// MARK: FileManager Properties (Files are stored on disk for `Video` object).
/*
These are file names (e.g., myFile.mp4, myFile.jpg)
*/
dynamic var previewLocalFileName: String?
dynamic var stitchedImageLocalFileName: String?
dynamic var placeholderLocalFileName: String?
/*
These are partial paths (e.g., bundleID/Feed/myFile.mp4, bundleID/Favorites/myFile.mp4)
They are used to build the full path/URL at runtime.
*/
dynamic var previewLocalFilePath: String?
dynamic var stitchedImageLocalFilePath: String?
dynamic var placeholderLocalFilePath: String?
// Other code...
}
这是我的代码来显示Video集合视图中的对象（注意：我使用RealmCollectionChange更新集合视图以删除和插入单元格）：
/// This view controller has a `collectioView` to show the favorites.
class FavoriteCollectionViewController: UIViewController {
// MARK: Properties
let favoriteList: FavoriteList = {
let realm = try! Realm()
return realm.objects(FavoriteList.self).first!
}()
// Realm notification token to update collection view.
var notificationToken: NotificationToken?
// MARK: Collection View
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return favoriteList.videos.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: FavoritesCollectionViewCell.reuseIdentifier, for: indexPath) as! FavoritesCollectionViewCell
cell.video = favoriteList.videos[indexPath.item]
return cell
}
// I pass this lst forward to the PlayerVC
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
if let playerVC = self.storyboard?.instantiateViewController(withIdentifier: "PlayerViewController") as? PlayerViewController {
// I pass the videos here.
playerVC.videos = favoriteList.videos
self.parent?.present(playerVC, animated: true, completion: nil)
}
}
// MARK: Realm Notifications
func updateUI(with changes: RealmCollectionChange<List<Video>>) {
// This is code to update the collection view.
}
}
最后，这是允许用户在所有内容之间播放和循环的代码Video对象：
/// This view controller uses `AVFoundation` to play the videos from `FavoriteCollectionViewController`.
class PlayerViewControllerr: UIViewController {
/// This `videos` is passed from `FavoriteCollectionViewController`
var videos = List<Video>()
// HELP: The app crashes here if I unfavorite a `Video`.
@IBAction func didToggleStarButton(_ sender: UIButton) {
let realm = try! Realm()
try! realm.write {
let videoToDelete = videos[currentIndexInVideosList] /// Get the video that is currently playing
realm.delete(videoToDelete)
}
}
}
最终我想要的是Video不喜欢的物体从 Realm 中完全删除。只是不确定在这种情况下如何/何时执行。
有什么想法吗？
Update 1
解决此问题的一个选项是：
- 制作一份非托管副本
Video复制，并使用它来驱动视图控制器的 UI。
我认为这可能起作用的方式是这样的：
Code:
/// This view controller uses `AVFoundation` to play the videos from `FavoriteCollectionViewController`.
class PlayerViewControllerr: UIViewController {
/// A button to allow the user to favorite and unfavorite a `Video`
@IBOutlet weak var starButton: UIButton!
/// This is passed from `FavoriteCollectionViewController`
var favoriteList: FavoriteList!
/// A copy of the `FavoriteList` videos to power the UI.
var copiedList: List<Video>!
var currentIndexOfVideoInCopiedList: Int!
override func viewDidLoad() {
super viewDidLoad()
// Make a copy of the favoriteList to power the UI.
var copiedVideos = [Video]()
for video in favoriteList.videos {
let unmanagedVideo = Video(value: video)
copiedVideos.append(unmanagedVideo)
}
self.copiedList.append(copiedVideos)
}
// HELP: The app crashes here if I unfavorite a `Video`.
@IBAction func didToggleStarButton(_ sender: UIButton) {
// Do the unfavoriting and favoriting here.
// An example of unfavoriting:
let realm = try! Realm()
try! realm.write {
let videoToDeleteFromFavoriteList = favoriteList.videos[currentIndexOfVideoInCopiedList] /// Get the video that is currently playing
realm.delete(videoToDeleteFromOriginalList)
}
// Update star button to a new image depending on if the `Video` is favorited or not.
starButton.isSelected = //... update based on if the `Video` in the `FavoriteList` or not.
}
}
有什么想法吗？
