SWIFT How to create a NSCoding Subclass and call i

问题:

I found this black of code on NSCoding and it almost does want I want it to. the link for where I found it is below. How do I create a NSCoding class and user in in other classes? The below code dies not work. I hope some can help me with this.

import Foundation
import UIKit


class User: NSObject, NSCoding {
    var name: String

    init(name: String) {
        self.name = name
    }

   required init(coder aDecoder: NSCoder) {

        self.name = aDecoder.decodeObjectForKey("name") as String
    }

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


//new class where I want to set and get the object

class MyNewClass: UIViewController {

    let user = User(name: "Mike")
    let encodedUser = NSKeyedArchiver.archivedDataWithRootObject(user)
    let decodedUser = NSKeyedUnarchiver.unarchiveObjectWithData(encodedUser) as User

}

//http://stackoverflow.com/questions/24589933/nskeyedunarchiver-fails-to-decode-a-custom-object-in-swift

回答1:

I'm cutting and pasting from my own project below. I have limited this to one string parameter to store to file. But you can more of different types. You can paste this into a single swift file and use it as the ViewController plus added classes to test. It demonstrates using NSCoding with swift syntax to save and retrieve data in an object.

import UIKit
import Foundation

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        var instanceData = Data()
        instanceData.name = "testName"
        ArchiveData().saveData(nameData: instanceData)
        let retrievedData = ArchiveData().retrieveData() as Data
        println(retrievedData.name)

    }
}

class Data: NSObject {

    var name: String = ""

    func encodeWithCoder(aCoder: NSCoder!) {
        aCoder.encodeObject(name, forKey: "name")
    }

    init(coder aDecoder: NSCoder!) {
        name = aDecoder.decodeObjectForKey("name") as String
    }

    override init() {
    }
}

class ArchiveData:NSObject {

    var documentDirectories:NSArray = []
    var documentDirectory:String = ""
    var path:String = ""

    func saveData(#nameData: Data) {
        documentDirectories = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
        documentDirectory = documentDirectories.objectAtIndex(0) as String
        path = documentDirectory.stringByAppendingPathComponent("data.archive")

        if NSKeyedArchiver.archiveRootObject(nameData, toFile: path) {
            //println("Success writing to file!")
        } else {
            println("Unable to write to file!")
        }
    }

    func retrieveData() -> NSObject {
        var dataToRetrieve = Data()
        documentDirectories = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
        documentDirectory = documentDirectories.objectAtIndex(0) as String
        path = documentDirectory.stringByAppendingPathComponent("data.archive")
        if let dataToRetrieve2 = NSKeyedUnarchiver.unarchiveObjectWithFile(path) as? Data {
            dataToRetrieve = dataToRetrieve2 as Data
        }
        return(dataToRetrieve)
    }
}