iOS Swift归档迁移：无法启用unarchivedObject新方法

归档代码修改（兼容新API） #

原有归档逻辑可直接沿用，archivedData(withRootObject:requiringSecureCoding:)目前未被弃用。若后续需启用安全编码，仅需将requiringSecureCoding设为true即可：

var selectedAmenities = [String: String]()

var archivedAmenities: Data?
do {
    archivedAmenities = try NSKeyedArchiver.archivedData(
        withRootObject: selectedAmenities,
        requiringSecureCoding: false
    )
} catch {
    print("Couldn't archive the Amenities.")
}

解归档代码修改（替换弃用API） #

用NSKeyedUnarchiver.unarchivedObject(ofClass:from:)替代弃用的unarchiveTopLevelObjectWithData方法。由于Swift字典[String: String]归档后对应Objective-C的NSDictionary类型，需指定目标类为NSDictionary.self，再转换为Swift字典：

var selectedAmenities = [String: String]()

guard let amenitiesData = theSite.amenities else {
    print("No amenities data to unarchive.")
    return
}

do {
    if let unArchivedAmenities = try NSKeyedUnarchiver.unarchivedObject(
        ofClass: NSDictionary.self,
        from: amenitiesData
    ) as? [String: String] {
        selectedAmenities = unArchivedAmenities
    } else {
        print("Unarchived data is not a valid [String: String] dictionary.")
    }
} catch {
    print("Couldn't unarchive the Amenities: \(error.localizedDescription)")
}

关键说明 #

• 规避强制解包风险：新增guard let校验数据是否存在，用as?替代as!防止类型转换崩溃
• 匹配正确归档类型：Swift字典归档后会转为NSDictionary，解归档时必须指定该类才能正确解析
• 优化错误排查：捕获错误时打印具体描述，便于定位问题

内容的提问来源于stack exchange，提问作者Kent