Question

我正在Swift的一个项目中工作，我将一组记录保存到核心数据，这很好。我保存它的方式如下。

public static func savePlaylistDetails(audio: [(title: String, healerName: String, trackUrl: String, trackID: String, imageUrl: String)] = [], playListName: String) {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext
    let newPlaylist = NSEntityDescription.insertNewObject(forEntityName: PlayList_DETAILS_ENTITY, into: context)

    let track = audio.map{ $0.trackID }
    print("Track",track)

    let trackId = track[0]

    print("ID is :", trackId)
    newPlaylist.setValue(playListName, forKey:"playlistName")
    newPlaylist.setValue(trackId, forKey:"trackID")

    do{
        try context.save()
        print("Saved.....")
    } catch{
        print("There was an error")
    }
}

如您所见，单个playList可能有多个轨道ID，这与上面的代码一起工作正常。但是我的要求是在更改实体名称或轨道ID后更新记录。我尝试按下面的顺序，但值重复。例如，如果我想在同一个播放列表中放置一组新曲目，并且如果我删除现有曲目，则会变得一团糟。

点击更新按钮时：

for item in selectedSongArray {
    let trackID = item.trackID
    print("Trck Id :",trackID)
    updateAnItemFromCoreData(playListName: playListName, trackId: trackID)
}

selectedSongArray包含我要保存的值。 update方法如下。

public static func updatePlaylistDetails(playlistName: String, trackID: String) {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: PlayList_DETAILS_ENTITY)
    request.predicate = NSPredicate(format: "playlistName = %@", playlistName)

    do {
        let results = try context.fetch(request)
        request.returnsObjectsAsFaults = false
        print("Results Count :", results.count)

        if(results.count > 0 ){
            for result in results as! [NSManagedObject] {
                result.setValue(playlistName, forKey: "playlistName")
                result.setValue(trackID, forKey: "trackID")

                try context.save();
                print("Saved.....")
            }
        } else {
          print("No Audios to save")
        }
    } catch{
        print("There was an error")
    }
}

更新核心数据中的现有记录

0 个答案: