How do i create a plist that I can access nicely in my app of array -> dictionary -> dictionary -> array -> mYClassInstances in swift?

Question

I need to save and load a nest of Array of Dictionaries of Dictionaries of array of mYClassInstances.

How should I store this object?

Answer 1

You cannot store Swift classes directly in a property list. You could store enough information about a class to reconstruct it later but I don't think that is what you are asking for. If you want to store an arbitrary graph of objects in a file, Cocoa offers the NSKeyedArchiver/Unarchiver classes.

Make sure that your MyClassInstance class is derived from NSObject and that it supports the NSCoding protocol. For example,

class MyClassInstances: NSObject, NSCoding, Printable {
    let name: String
    init(name: String) {
        self.name = name
    }

    @objc func encodeWithCoder(aCoder: NSCoder) {
        aCoder.encodeObject(name, forKey: "NAME")
    }

    @objc required init(coder decoder: NSCoder) {
        self.name = decoder.decodeObjectForKey("NAME") as! String
    }

    override var description: String {
        return "MyClassInstance.name = \(name)"
    }
}

Then assuming you have your array of dictionaries, of dictionaries, of arrays of instances stored in a variable named nest; you would could store all of your objects with this call.

let temporaryDirectory = NSTemporaryDirectory()
let temporaryFile = temporaryDirectory.stringByAppendingPathComponent("SO-test.archive")
NSKeyedArchiver.archiveRootObject(nest, toFile: temporaryFile)

Reading back the graph of objects uses this call. Note that it is important to get the typecasting correct.

let nest2 = NSKeyedUnarchiver.unarchiveObjectWithFile(temporaryFile) as! [[String: [String: [MyClassInstances]]]]

Here is a Playground screen capture.