Dictionary saved to NSUserDefaults always returns nil

Question

I'm trying to save a dictionary to NSUserDefaults using the setObject() function but when I use the objectForKey() function to retrieve the dictionary it returns nil. Why is this happening?

var data = NSUserDefaults.standardUserDefaults();
var scoreboard = [Int : String]()
let scores = "scoresKey"

scoreboard[3] = "spencer"
scoreboard[6] = "brooke"
scoreboard[11] = "jason"

data.setObject(scoreboard, forKey: scores)
data.objectForKey(scores) // Returns nil

You need to test it on a real project. Not playground – Leo Dabus May 02 '16 at 05:56 — Leo Dabus, May 02 '16 at 05:56

score 1 · Accepted Answer · edited May 23 '17 at 10:33

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The first problem was that it's not possible to use NSUserDefaults in a Playground.

See: https://stackoverflow.com/a/31210205/3498950

A second problem is found when the code above runs in a normal iOS project. It throws an NSInvalidArgumentException since the dictionary was a non-property list object because the keys needed to be of type String.

Although NSDictionary and CFDictionary objects allow their keys to be objects of any type, if the keys are not string objects, the collections are not property-list objects.

See: "What is a Property List?" in the Apple Docs

edited May 23 '17 at 10:33

Community

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answered May 02 '16 at 06:47

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Did you try the exact code above? It doesn't work for me. It throws an exception: "Attempt to set a non-property-list object { 6 = brooke; 3 = spencer; 11 = jason; } as an NSUserDefaults/CFPreferences value for key scoresKey". – Kurt Revis May 02 '16 at 06:55
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(Which is because "property-list" dictionaries must have strings as keys. See ["What is a property list?"](https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/PropertyLists/AboutPropertyLists/AboutPropertyLists.html#//apple_ref/doc/uid/10000048i-CH3-54303) in the Apple docs, and also [this question](http://stackoverflow.com/questions/22704678/nsdictionary-with-nsnumber-to-nsstring-mapping-is-non-property-list-object).) – Kurt Revis May 02 '16 at 07:05

Dictionary saved to NSUserDefaults always returns nil

1 Answers1