CODEWITHSUNDEEP
iosswiftnsarraynsdictionary
arled
arled

Reputation: 2690

Add specific elements from an NSDictionary to an NSArray

So I have this NSDictionary itemsDict(in Swift):

var itemsDict : NSDictionary = [:] // Dictionary
var Sections : NSArray = [] // Array

itemsDict = [
["News"]:["a":"www.hello.co.uk","b":"www.hello.com"],
["Sport"]:["c":"www.hello.co.uk","d":"www.hello.com"],
    ]

    print (itemsDict)

This is how the structure of the dictionary looks like:

{
        (
        News
    ) =     {
        a = "www.hello.co.uk";
        b = "www.hello.com";
    };
        (
        Sport
    ) =     {
        c = "www.hello.co.uk";
        d = "www.hello.com";
    };
}

From the dictionary above I want to be able to populate an NSArray with only the - [News,Sports] elements. I've tried this and a few other methods but they just don't seem to cut it. My Swift skills are not that advanced and I hope this post make sense.

Sections = itemsDict.allKeysForObject(<#anObject: AnyObject#>)

Upvotes: 0

Views: 2373

Answers (1)

Mike S
Mike S

Reputation: 42325

To get an Array of all Strings in your Dictionary's keys, you can use the allKeys property of NSDictionary along with a reduce function, like so:

var itemsDict = [
    ["News"]:["a":"www.hello.co.uk","b":"www.hello.com"],
    ["Sport"]:["c":"www.hello.co.uk","d":"www.hello.com"],
]

let keys = (itemsDict.allKeys as [[String]]).reduce([], combine: +)

println(keys)

Outputs:

[News, Sport]

However, I don't see a good reason to use Arrays of Strings as your Dictionary keys. Instead, I'd just use Strings as keys directly, like so:

var itemsDict = [
    "News":["a":"www.hello.co.uk","b":"www.hello.com"],
    "Sport":["c":"www.hello.co.uk","d":"www.hello.com"],
]

In which case, getting an Array of the Dictionary's keys is as simple as:

let keys = itemsDict.keys.array

Note: I'm using the keys property here and the allKeys property earlier because this is a native Swift Dictionary while the earlier code is an NSDictionary due to its use of NSArrays for keys.

Upvotes: 1

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