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I am trying to get an array o keys from a dictionary where the array is sorted by values. For example:

//dictionary contains [alpha:C],[beta:A],[gamma:B]

My array should return:

//[beta, gamma, alpha]

I tried:

let keys = Array(myDictionary.keys).sort({ (a,b) -> Bool in
        a.compare(b) == .OrderedAscending
    })

but this returns the order by keys:

//[alpha, beta, gamma]
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1 Answer 1

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2

Given your dictionary

let dict = ["alpha":"C","beta":"A","gamma":"B"]

You can sort the keys by value with this code

let keysSortedByValue = dict.sort { $0.1 < $1.1 }.map { $0.0 }

// ["beta", "gamma", "alpha"]

Update

This screenshot to answer to your comment below

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4 Comments

Although i clicked "accepted" there is something that i don't understand. This: let dict = ["alpha":"alpha","beta":"beta","gamma":"gamma"] returns first beta then alpha and the gamma. It seems your advise does not work with strings properly
@Mic: I just tested it and it is returning ["alpha", "beta", "gamma"]. Please see the screenshot I added to my answer. Are you sure you are using exactly this input? I suspect you are using some uppercase letters...
You was correct. Because of many tests there was a 0 instead of 1 and I missed. Answer is accepted. Sorry for this. In case I gona use uppercase letters is something that I have to mind?
@Mic: if you want case-insensitive String sorting, you could apply lowerCaseString to the arguments in the sorting closure, e.g. let keysSortedByValue = dict.sort { $0.1.lowercaseString < $1.1.lowercaseString }.map { $0.0 }.

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