Swift store array with UserDefaults

Question

So I'm trying to store some posts id's basically so I can know what the user has read so I can show a "seen" button.

var actual_data = UserDefaults.standard.array(forKey: "seen_posts")
UserDefaults.standard.setValue(actual_data?.insert(321, at: 0), forKey: "seen_posts")

I have tried this, but it doesn't seem to work, Ambiguous use of 'insert(_:at:)'

Updated

var actual_data = UserDefaults.standard.array(forKey: "seen_posts")
UserDefaults.standard.set(actual_data?.append(["miodrag"]), forKey: "seen_posts")

move `actual_data?.insert(321, at: 0)` to the line above it and set actual_data forKey — Leo Dabus, Jan 21 '17 at 19:03
just omit data from it or add array which it is not needed as you can always check its type. BTW the conventions is camelCase (not underscore) — Leo Dabus, Jan 21 '17 at 19:07
this may help you http://stackoverflow.com/questions/25179668/how-to-save-and-read-array-of-array-in-nsuserdefaults-in-swift — user6788419, Jan 21 '17 at 19:07
... and don't use `setValue:forKey` unless you can explain why KVC is explicitly needed. — vadian, Jan 21 '17 at 19:09
@vadian can you post an example on how to set an array for UserDefaults, basically needs to contain an array with IDS — Uffo, Jan 21 '17 at 19:10
`UserDefaults.standard.set(actual_data, forKey: "seen_posts")` — Leo Dabus, Jan 21 '17 at 19:10
Make sure you are not testing it using a playground (it doesn't work) — Leo Dabus, Jan 21 '17 at 19:12
@LeoDabus I need to read the current data and add a value to the array and save it — Uffo, Jan 21 '17 at 19:13

vadian · Accepted Answer · 2017-01-21T19:30:29.020

2

The reason of the error is that the compiler cannot infer the type of the array.

Spend an extra line to read, change and write the data, for example:

let defaults = UserDefaults.standard
var seenPosts : [Int]
if let actual = defaults.array(forKey: "seen_posts") as? [Int] {
     seenPosts = actual
} else {
     seenPosts = [Int]() 
}
seenPosts.insert(321, at: 0)
defaults.set(seenPosts, forKey: "seen_posts")

or if the default key seen_posts is registered – as recommended – simpler

let defaults = UserDefaults.standard
var seenPosts = defaults.array(forKey: "seen_posts") as! [Int]
seenPosts.insert(321, at: 0)
defaults.set(seenPosts, forKey: "seen_posts")

edited Jan 21 '17 at 19:30

answered Jan 21 '17 at 19:16

vadian

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let array = defaults.object(forKey:"seen_posts") as? [String] ?? [String]() debugPrint(array) So I have added this to test it, and I get an empty array – Uffo Jan 21 '17 at 19:30
According to your (first) code the array is `[Int]`. – vadian Jan 21 '17 at 19:31

Swift store array with UserDefaults

1 Answers1