How to keep the same order after groupby array to Dictionnary swift

Question

I have array type like this :

let types = ["Notification","Type1","Type2","Type3"..."TypeN"]

And i'm using this extension to grouprBy an array by type

extension SequenceType {
    func groupBy<U : Hashable>(@noescape keyFunc: Generator.Element -> U) -> [U:[Generator.Element]] {
        var dict: [U:[Generator.Element]] = [:]
        for el in self {
            let key = keyFunc(el)
            if case nil = dict[key]?.append(el) { dict[key] = [el] }
        }
        return dict
    }
}

The problem is i'm getting weird order, The notification type is not the first element in my dictionary. Is possible to keep the same order of my types array into the dictionary ?

As answered by Sahil, a dictionary is *not* sortable. See also http://stackoverflow.com/questions/25377177/sort-dictionary-by-keys, http://stackoverflow.com/questions/24090016/sort-dictionary-by-values-in-swift?lq=1 and many similar Q&As. — Eric Aya, Jun 13 '16 at 15:13

score 2 · Accepted Answer · answered Jun 13 '16 at 15:01

2

From Apple docs:

Unlike items in an array, items in a dictionary do not have a specified order.

So, you can't keep them in sorted order in a dictionary.

answered Jun 13 '16 at 15:01

Sahil Kapoor

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Thank's, is there possible to insert element at first position into the dictionary because i'm also having trouble to do that – YouSS Jun 13 '16 at 15:03
3

There are no positions in a dictionary, only key-value pairs. – Sahil Kapoor Jun 13 '16 at 15:05
How the keys are sorted in dictionary ? – YouSS Jun 13 '16 at 15:07
1

@Youssef.Z The keys are not sorted in a dictionary. Nothing about a dictionary is sorted. – rmaddy Jun 13 '16 at 15:27

How to keep the same order after groupby array to Dictionnary swift

1 Answers1