Question

我正在关注iOS教程，并且我遇到了问题。我有这个代码用于反射，我的应用程序中的模型对象：

struct Reflection {
let title: String
let body: String
let author: String
let favorite: Bool
let creationDate: Date
let id: UUID
}

extension Reflection {
var plistRepresentation: [String: AnyObject] {
    return [
        "title": title as AnyObject,
        "body": body as AnyObject,
        "author": author as AnyObject,
        "favorite": favorite as AnyObject,
        "creationDate": creationDate as AnyObject,
        "id": id as AnyObject
    ]
}

init(plist: [String: AnyObject]) {
    title = plist["title"] as! String
    body = plist["body"] as! String
    author = plist["author"] as! String
    favorite = plist["favorite"] as! Bool
    creationDate = plist["creationDate"] as! Date
    id = plist["id"] as! UUID
}
}

然后我有这个存储控制器：

class StorageController {
fileprivate let documentsDirectoryURL = FileManager.default
    .urls(for: .documentDirectory, in: .userDomainMask)
    .first!

fileprivate var notesFileURL: URL {
    return documentsDirectoryURL
        .appendingPathComponent("Notes")
        .appendingPathExtension("plist")
}

func save(_ notes: [Reflection]) {
    let notesPlist = notes.map { $0.plistRepresentation } as NSArray
    notesPlist.write(to: notesFileURL, atomically: true)
}

func fetchNotes() -> [Reflection] {

    guard let notePlists = NSArray(contentsOf: notesFileURL) as? [[String: AnyObject]] else {
        print("No notes")
        return []
    }
    print("Notes found")
    return notePlists.map(Reflection.init(plist:))
}
}

当我调用save()并尝试写入plist时，我没有收到任何错误。但是，当我调用fetchNotes()时，它会打印＆＃34; No Notes＆＃34;，暗示使用这些内容的数组为nil或者无法将其强制转换为字典。为什么会这样？

Answer 1

UUID不是属性列表的有效元素。您需要将其作为字符串存储在属性列表中，例如

“id”: id.uuidString as AnyObject

并将其转换回来：

id = UUID(uuidString: plist[“id”] as! String)!

为什么这个plist读/写失败？

1 个答案: