Cannot retrieve correctly saved NSKeyArchived Object in Swift3 - ios

Question

I cannot retrieve an object saved as a NSkeyed archive in Swift 3, and am scracthcing my head. The object is successfully saved as a plist, but returned as nil when loading back in.
Here is the code I use:
The class itself to be saved as an object is fairly easy:
import Foundation
class ItemList:NSObject, NSCoding {
var name: String = "" //Name of the Item list
var contents: [Int] = [] //Ints referencing the CoreData PackItems
init (listname:String, ContentItems:[Int]) {
self.name=listname
self.contents=ContentItems
}
//MARK: NSCoding
public convenience required init?(coder aDecoder: NSCoder) {
let thename = aDecoder.decodeObject(forKey: "name") as! String
let thecontents = aDecoder.decodeObject(forKey: "contents") as! [Int]
self.init(listname: thename,ContentItems: thecontents)
}
func encode(with aCoder: NSCoder) {
aCoder.encode(self.name,forKey:"name")
aCoder.encode(self.contents, forKey: "contents")
}
}
The code to load and save the object:
class FileHandler: NSObject {
class func getDocumentsDirectory() -> URL {
let filemgr = FileManager.default
let urls = filemgr.urls(for: .documentDirectory, in: .userDomainMask)
let result:URL = urls.first!
return result
}
///This returns the contents of the handed file inside the Documents directory as the object it was saved as.
class func getFileAsObject(filename:String) -> AnyObject? {
let path = getDocumentsDirectory().appendingPathComponent(filename)
if let result = NSKeyedUnarchiver.unarchiveObject(withFile: path.absoluteString) {
//Success
print("Loaded file '"+filename+"' from storage")
return result as AnyObject?
} else {
print("Error: Couldn't find requested object '"+filename+"' in storage at "+path.absoluteString)
return nil
}
}
///This saves the handed object under the given filename in the App's Documents directory.
class func saveObjectAsFile(filename:String, Object:AnyObject) {
let data = NSKeyedArchiver.archivedData(withRootObject: Object)
let fullPath = getDocumentsDirectory().appendingPathComponent(filename)
do {
try data.write(to: fullPath)
print("Wrote file '"+filename+"' to storage at "+fullPath.absoluteString)
} catch {
print("Error: Couldn't write file '"+filename+"' to storage")
}
}
}
...and finally, this is what I do to call it all up:
let testobject:ItemList = ItemList.init(listname: "testlist", ContentItems: [0,0,1,2])
FileHandler.saveObjectAsFile(filename:"Test.plist",Object:testobject)
let tobi = FileHandler.getFileAsObject(filename:"Test.plist") as! ItemList
Alas, I get this as output:
Wrote file 'Test.plist' to storage at file:///…/data/Containers/Data/Application/6747B038-B0F7-4B77-85A8-9EA02BC574FE/Documents/Test.plist
Error: Couldn't find requested object 'Test.plist' in storage at file:///…/data/Containers/Data/Application/6747B038-B0F7-4B77-85A8-9EA02BC574FE/Documents/Test.plist
Note that this is my own output -- so I do (and have checked) that the file was created correctly. But it just won't load. Can anyone tell me what I am doing wrong?

Answer 1

The problem is with the path you pass to unarchiveObject(withFile:).
Change:
if let result = NSKeyedUnarchiver.unarchiveObject(withFile: path.absoluteString) {
to:
if let result = NSKeyedUnarchiver.unarchiveObject(withFile: path.path) {
On a side note, you should use symmetric APIs for your writing and reading logic. When you write the data you archive a root object to a Data object and then write the Data object to a file. But when reading, you directly unarchive the object tree given a file path.
Either change your writing code to use archiveRootObject(_:toFile:) or change the reading code to load the Data from a file and then unarchive the data. Your current code works (once you fix the path issue) but it's not consistent.