使用NSKeyedUnarchiver unarchivedObject(ofClass:from :)取消存档数组 [英] Unarchive Array with NSKeyedUnarchiver unarchivedObject(ofClass:from:)

问题描述

自升级到Swift 4.2之后，我发现许多NSKeyedUnarchiver和NSKeyedArchiver方法已被弃用，我们现在必须使用类型方法static func unarchivedObject<DecodedObjectType>(ofClass: DecodedObjectType.Type, from: Data) -> DecodedObjectType?取消存档数据.

Since upgrading to Swift 4.2 I've found that many of the NSKeyedUnarchiver and NSKeyedArchiver methods have been deprecated and we must now use the type method static func unarchivedObject<DecodedObjectType>(ofClass: DecodedObjectType.Type, from: Data) -> DecodedObjectType? to unarchive data.

我已经成功地成功归档了我的定制类WidgetData的数组，该数组是NSObject的子类:

I have managed to successfully archive an Array of my bespoke class WidgetData, which is an NSObject subclass:

private static func archiveWidgetDataArray(widgetDataArray : [WidgetData]) -> NSData {

    guard let data = try? NSKeyedArchiver.archivedData(withRootObject: widgetDataArray as Array, requiringSecureCoding: false) as NSData
        else { fatalError("Can't encode data") }

    return data

}

当我尝试取消存档这些数据时出现问题:

The problem comes when I try to unarchive this data:

static func loadWidgetDataArray() -> [WidgetData]? {

    if isKeyPresentInUserDefaults(key: USER_DEFAULTS_KEY_WIDGET_DATA) {

        if let unarchivedObject = UserDefaults.standard.object(forKey: USER_DEFAULTS_KEY_WIDGET_DATA) as? Data {

            //THIS FUNCTION HAS NOW BEEN DEPRECATED:
            //return NSKeyedUnarchiver.unarchiveObject(with: unarchivedObject as Data) as? [WidgetData]

            guard let nsArray = try? NSKeyedUnarchiver.unarchivedObject(ofClass: NSArray.self, from: unarchivedObject as Data) else {
                fatalError("loadWidgetDataArray - Can't encode data")
            }

            guard let array = nsArray as? Array<WidgetData> else {
                fatalError("loadWidgetDataArray - Can't get Array")
            }

            return array

        }

    }

    return nil

}

但是这失败了，因为不允许使用Array.self而不是NSArray.self.我在做什么错，我该如何解决才能取消对我的Array的存档?

But this fails, as using Array.self instead of NSArray.self is disallowed. What am I doing wrong and how can I fix this to unarchive my Array?

推荐答案

您可以使用unarchiveTopLevelObjectWithData(_:)取消存档archivedData(withRootObject:requiringSecureCoding:)归档的数据. (我相信现在还不建议使用.)

You can use unarchiveTopLevelObjectWithData(_:) to unarchive the data archived by archivedData(withRootObject:requiringSecureCoding:). (I believe this is not deprecated yet.)

但是在显示一些代码之前，您最好:

But before showing some code, you should better:

• 避免使用NSData，请改用Data

避免使用try?来放置对调试有用的错误信息

Avoid using try? which disposes error info useful for debugging

删除所有不需要的演员

尝试一下:

private static func archiveWidgetDataArray(widgetDataArray : [WidgetData]) -> Data {
    do {
        let data = try NSKeyedArchiver.archivedData(withRootObject: widgetDataArray, requiringSecureCoding: false)

        return data
    } catch {
        fatalError("Can't encode data: \(error)")
    }

}

static func loadWidgetDataArray() -> [WidgetData]? {
    guard
        isKeyPresentInUserDefaults(key: USER_DEFAULTS_KEY_WIDGET_DATA), //<- Do you really need this line?
        let unarchivedObject = UserDefaults.standard.data(forKey: USER_DEFAULTS_KEY_WIDGET_DATA)
    else {
        return nil
    }
    do {
        guard let array = try NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(unarchivedObject) as? [WidgetData] else {
            fatalError("loadWidgetDataArray - Can't get Array")
        }
        return array
    } catch {
        fatalError("loadWidgetDataArray - Can't encode data: \(error)")
    }
}

---

但是，如果要制作新应用，则最好考虑使用Codable.

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