Chapter 16, P292: NSKeyedUnarchiver.unarchivedObject

iOS Programming: The Big Nerd Ranch Guide (6th Edi 16. Saving, Loading, and Application States
1

Hi all,

I am referring to the following textbook reference:

init() {
if let archivedItems = NSKeyedUnarchiver.unarchiveObject(withFile: itemArchiveURL.path) as? [Item] {
allItems = archivedItems
}
}

I am getting an error message in XCODE as this method is now obsolete. Can someone please assist in what new commands I need to enter in order to successfully restore the Items in this example of the book?

It seems that saving data I have managed to achieve, but retrieving the data is impossible.

Please Help as am new to iOS programming!

Best Regards,

Demetris

2

According to the documentation, that function has been superseded by the following functions.

class func unarchiveTopLevelObjectWithData(_ data: Data) throws -> Any?

static func unarchivedObject<DecodedObjectType>(ofClass cls: DecodedObjectType.Type, from data: Data) throws -> DecodedObjectType? where DecodedObjectType : NSObject, DecodedObjectType : NSCoding

static func unarchivedObject(ofClasses classes: [AnyClass], from data: Data) throws -> Any?

Use one of them. To use one, you need to create a data object from the archive file first.

4

Thank you ibex10, can you please show me how to rewrite the code in order to make the book program functional? I have tried but with no success.

5 
init() {
    if let data = try? Data(contentsOf: itemArchiveURL) {
        if let archivedData = try? NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(data) as? [Item] {
            allItems = archivedData ?? [Item]()
        }
    } 
}

This worked for me. I’m still a novice so there are probably better ways to do it.