Cache Array of Custom Objects in Swift3

Question

I need to persist an array of custom objects from session to session for a user. The array will be filled with 1-14 fairly simple and lightweight custom swift objects like so:

[Obj1, Obj2, Obj3]

What I want to do is when viewWillDisappear is called, persist this data so that when the user comes back to the screen, I can use these exact objects again. What is the best way to do this? I've looked into using core data, but I don't want to setup a data model for these objects, just store them as is without any relationships or anything.

Please note that the app makes use of a very computationally taxing algorithm, of which these objects play a central role. As such, I need to keep these objects as light as possible. Therefore, I don't want to make the objects conform to NSCoding as it isn't necessary to the central role of the object

Answer 1

If making your class an Objective-C class that conforms to NSCoding proves to actually have a substantial performance impact (I'm skeptical), then you can make a second container that subclasses NSCoding that's used solely for storage. Add an initializer to your current lightweight Swift class/struct that initializes the instance from this container object, and vice versa. Any time you need to serialize/deserialize, you just use this container object as an intermediate.

This buys you the functionality at minimal cost when reading/writing, but leaves regular usage performance unaffected.

Answer 2

如果可以使对象成为NSObject的子类，则可以使其符合NSCoding并使用NSKeyedArchiver和NSKeyedUnarchiver序列化和反序列化对象。