I added this extension to make it a more or less identical API signature: extension NSKeyedUnarchiver { static func insecureUnarchivedObject<DecodedObjectType>( ofClass cls: DecodedObjectType.Type, from data: Data ) throws -> DecodedObjectType? where DecodedObjectType : NSObject, DecodedObjectType : NSCoding { let unarchiver = try NSKeyedUnarchiver.init(forReadingFrom: data) unarchiver.requiresSecureCoding = false let decodedType = unarchiver.decodeObject(forKey: NSKeyedArchiveRootObjectKey) as? DecodedObjectType return decodedType } }